noun a person who has no real friends their own age and therefore hangs out with their kids friends or their siblings friends (not to be confused with a pedophile, milf, cougar or a douche bag, though loser may be an acceptable synonym)
Steven graduated with me in the 90's but he goes skateboarding with my little brother who graduated last year, he's such a lose bag.
what the kids aren't saying these days
Yo, you're such a lose bag.
WTF is a lose bag?