If you are stupid enough to fail the Quick Time Event involving the rat in the sewer, you cause enough noise to attract a PLR soldier who blows you away. Just before you die, you manage to flip the bird at the offending rat.
In "Rock and a Hard Place", while riding on the back of a transport vehicle a sleeping squadmate by the name of Christian Matkovic will be woken up, prompting this response:
Some of the American soldier's multiplayer dialogue is hilarious:
Soldier (upon spotting an enemy Support): "Yeah- yeah I see you, ya little fuck! We got a machinegunner in the area."
Soldier (upon spotting an enemy Engineer): "Roger, umm... We have spotted- Yeah no shit, umm, We've spotted anti-tank troops, repeat, those are anti-tank troops, over."
Soldier: "ENEMY COCKSUCKERS AHEAD!"
Soldier (upon requesting a ride from a passing vehicle): Pick me. The fuck. Up.