Why can orphans not play bingo?
Because they can't get a full house.
Orphan Bingo
Explanation
Explain Bear
Hey, chucklehead! This is Explain Bear here! Orphans can't get a "full house" in bingo because they, uh, don't have parents, like, a mom and dad, get it? You know you're the type of guy to still use Internet Explorer and watch the install bar fill up with excitement.