i Register
In some senses, plonker is marked as derogatory, slang, dated, UK. Watch for register when choosing this word.
noun
A fool.
“You kept the hat! You bloody plonker!” “Fuck me.” “And now look at you, bouncing off the cars like a bouncing idiot.” “Fucking hell!” “Is he gonna be alright?”
A penis.
A man who sanctions sexual relationships between his girlfriend and his male friends.
One who plonks.