beats me

Etymology
A shortening of it beats me

Phrase

 * 1)  I don't know; I have no idea.
 * Do you have any idea what "tergiversate" means? Beats me!
 * Beats me how he finds out when we're goofing off.

Usage notes

 * This expression is nearly always used in the present tense, first person singular, as given above.

Synonyms

 * search me