One of the answers to "What Isa Thunk?" is that Thunk Is Past Tense of Think.
;->
The name? The Jargon File mentions that thunk is the "past tense of `think' at two in the morning."
Yeah.. I sometimes answer, "Sunir, what the heck were you thinking?!" with "Think. Think. Thunk." -- Sunir Shah
"Thunk" appears in Samuel Clemens's book Huckleberry Finn. During the raft ride down the Mississippi for long periods Huck and Jim "just sat around and thunk".
If you treat "think" as a regular strong verb, "thunk" is the past participle, not the past tense. But the past tense is "thank", which clashes with another verb. (Not that there aren't other verbs that clash with each other, but...) Fortunately the distinction between past participle and past tense is eroding, so maybe someday "thunk" will be the correct past tense of "think" - at least in some of the Anglic languages (or whatever they get called).
See original on c2.com 