Sucking dick is a vulgar slang term for performing oral sex on a man. Telling someone to suck a dick is a strong insult meaning “Screw you! The word dick has been a slang term for a man or fellow since the 16th century. It is likely that its meaning expanded (pardon the pun) to “penis” in the mid-19th century—at least as recorded, as it was certainly spoken well before then.The expression sucking dick rose by the 1920s, apparently first used by sex workers