Leeches.
Creepy worms that suck your blood - who's idea was that? Come on! I can't take a swim without getting attacked by tiny, blood eating snakes?
Also, people who benefit from your work in a devious way. "Hey dude, what do you think about this?" AKA, could you finish my work for me and let me take the credit?!
Leeches (literal and figurative) Suck!
