A sergeant and a soldier goes to brothel. Since brothel doesnt have lights, sergant orders the soldier to hold a light while he fucks the prostitute.

After humb and dump several tries, sergeant complains he cant do it while the soldier looks at him. The soldier asks if it's okay to take the chance and sergeant let him do it.

This time sergant holds the light while the soldier is doing ficki ficki. After several hours of sex, both the whore and soldier ends up satisfied.

Then the sergant approaches and says:

See, that's how you hold a light you incompetent bastard!