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Chiefly British: A male paedophile (pedophile) - likes sexual activity with underage boys.
When I was twelve I was walking my bike in the park when this plonker came up to me said I had lovely legs, did I want to go with him. I got on my bike and took off! (This really happened!)
by Michiwawa February 09, 2012
a poo that is so heavy that makes a massive splash with the toilet water that hits your arse and makes you feel wet.
aw man i just took a massive plonker!
by 56413257658374211453 August 26, 2007
A stupid person
A penis
Look at that fucking plonker!
I stuck my big fat plonker up her arse!
by KL June 27, 2003
A polite, in mixed company, and alternative word for stupid cunt and wanker.
John is a plonker.
by Dick Splash August 17, 2003