The All Summer Long hitmaker joined forces with Armstrong, actor Robin Williams and comedian Lewis Black for a tour of the Middle East to boost soldier morale and they were all shacked up in a small bunk for several days.
While the rocker admits he had a blast performing for the troops, he didn't particularly like having Armstrong as a roommate.
He tells GQ magazine, "I've been over there for the military so many times, and oh, I can't tell you, I hate that region. At least in Vietnam (during the war) they had the f**king beers and dope. Robin Williams went to Iraq with us. It was him and Lewis Black and Lance Armstrong. And we got stuck at this base. Like, there was literally four bunk beds lined up, and we each had a handler.
"It was like camp. You know, it's dark, and Robin and Lewis just started making jokes, like, about our ordeal. And then Lance Armstrong won't stop farting. So every time there'd be just a moment of silence and it'd be like (fart noise)."