|“||Should've just brought the grenade launcher.||”|
The grenade launcher is first seen inside a weapons box in the trunk of The Impala in the Pilot episode. This version is a CAW 40mm airsoft grenade launcher. In subsequently appearances, it is replaced with a genuine DefTech 37mm launcher.
In Wendigo, while on a hunt Dean and Sam collect several weapons from the Impala and put them in a packing bag to take on the trip. The grenade launcher can be briefly seen in the trunk whilst Dean is gathering weapons from the trunk.
In Skin, while on a shapeshifter hunt Dean is knocked out by the shapeshifter and locked in its lair. It then takes his form to ambush Sam. During the ruse the shapeshifter checks out the Winchesters' arsenal in the trunk of The Impala. It was impressed by their arsenal. One of the weapons it saw was the grenade launcher.
In Home, while rescuing a family from a poltergeist Sam gets trapped in the house alone with it. Dean goes to the trunk of the Impala to get some weapons and rescue Sam. The grenade launcher can be briefly seen in the trunk whilst Dean is gathering weapons from the trunk.
In The Monster at the End of This Book, Sam and Dean show Chuck Shurley the arsenal of weapons in The Impala's trunk to prove they are the real Sam and Dean. The grenade launcher can be seen in the trunk.
In The Man Who Knew Too Much, after Castiel destroys The Wall in Sam's head blocking the memories of Hell Sam falls into a coma. Sam ends up in a dream like state with amnesia fighting to wake up. While trapped in his mind Soulless Sam attempts to kill him. The amnesic Sam remembers the arsenal in the Impala's trunk. While gathering weapons the grenade launcher can be seen. Sam doesn't choose it and instead takes a shotgun and his Taurus Model 99.
In The One You've Been Waiting For, Dean picks up the grenade launcher for the first time with the intent on using it against a group of Thules. Unfortunately, Sam tells him to leave it in the trunk, as they need to be stealthy which leaves Dean visibly disappointed causing Sam to promise him they will get to use it at some point. Once they enter the Thules' base of operation, they are immediately captured and disarmed, leading Dean to say "should've brought the grenade launcher."
In LOTUS, Arthur Ketch uses a grenade launcher to destroy a Secret Service vehicle and rescue the Winchesters and Castiel. Dean later asks if Arthur used a grenade launcher with obvious enthusiasm which Arthur confirms.
In Regarding Dean, when a memory-less Dean opens the trunk, he finds that Rowena has labeled the grenade launcher with "NO!" Even without his memory, Dean appears to be disappointed about not being able to use the grenade launcher.
In Twigs & Twine & Tasha Banes, Dean shows the contents of the Impala's trunk to Max Banes who is impressed by the grenade launcher. While Dean confirms that it is in fact a grenade launcher, he regretfully tells Max they need the witch-killing bullets instead.
In Who We Are, an excited Dean finally uses the grenade launcher to blow a hole in a bunker wall in order to reach the sewers beyond. This allowed him to hit the bunker's manual override and end the fatal lockdown imposed by Arthur Ketch.
In The Heroes' Journey, after being reminded that they are normal people now, Dean decides that they need the grenade launcher and eagerly removes it from the Impala's trunk. As Sam loads the weapons bag, Dean enjoys playing around with the grenade launcher. However, Dean has to put the grenade launcher down in the bathroom after getting sick and it is taken by Cutty who uses it to capture Dean. The grenade launcher may have been destroyed when Garth blew up the monster fight club.
- Season 6
- Season 8
- Season 11
- Season 12
- Season 15
- Despite its usefulness and potential to solve numerous cases throughout the years, the grenade launcher was never touched, leading to a running gag within the fandom.
- Following Season 12, fans continue to demand for the use of the grenade launcher.
- In Who We Are, Dean has finally used this to blow up a wall in the Men of Letters bunker. Dean also quips "yippie kiya mother...!" when doing it. This is the catchphrase of John McClaine from the Die Hard series and what Dean said when he killed Elias Finch with the Colt.
- In LOTUS, when Dean gets excited over Arthur Ketch using a grenade launcher, Sam can be seen to briefly raise a pacifying hand to Dean's enthusiasm.
- In Who We Are, Dean calls his plan to use the grenade launcher "big, beautiful and dumb" and then states that he has had the grenade launcher for "so long" and has waited for the perfect moment to use it. As he prepares to fire, Dean also calls the grenade launcher "beautiful".
- When Dean finally used the grenade launcher in Who We Are, the explosion left him with a leg injury, particularly to his knee which appeared to be fairly cut up. It was initially treated by Alex Jones who is a nursing student. This leg injury hobbled Dean to the point that he didn't take part in the Assault on the British Men of Letters compound and hindered him in his fight with Arthur Ketch. In All Along the Watchtower, Dean continued to have this injury until Castiel noted the pain it caused Dean and healed his leg and the cuts from his fight with Arthur.