Every time I see this meme, the only thing I think is "would the round even fire? It's not a closed system... How integral is air to the ignition process? There are some guns that can fire under water, but I don't think it's a majority, I should look that up later (I never do), those might work in space. This looks like a Beretta m9 to me, God I hated the m9 giant fucking heavy ass gun, it didn't even need to be that big 9mm isn't a large round.... "
I also sometimes overthink jokes.
ETA: Finally looked it up, yes they would because modern bullets contain their own oxidizer, which means underwater works too. Huh, TIL.