1. thonk - Verb
2. thonk - Interjection
thonk (third-person singular simple present thonks, present participle thonking, simple past and past participle thonked)
(Internet slang) To think deeply; to ponder.
I had to thonk long and hard before coming to a decision.
thonk
(Internet slang) Used ironically in reaction to a conclusion seen as illogical.
That guy robbed me once already, so he won't do it again. Thonk.