Crossword Genius

"That'll be the day!" (4)

Ross

I think it could be either:

asif

ibet

(Other definitions for asif that I've seen before include "I very much doubt it!" , "yeah, right!" , "Common name in Pakistan" .)

I've seen this clue in the Universal, the LA Times, the L.A. Times Daily, the Newsday and the USA Today.
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