For anyone unfamiliar, barrel obstructions can be very dangerous as they can result in unsafe pressures when firing.
Here a soldier has put condoms on the ends of these machine gun barrels to prevent sand and dust from entering. Presumably before riding in a convoy along a dirt road.
“wait… If that condom is here instead of the barrel cover… What did I put on my dick yesterday in the shower?! Shit… I need to make a phone call!”