A phrase that expresses extreme fatigue. The word "beat" (though it is used to describe tiredness) is often used to describe slutty women who have sex often and look liketrash (see bro-ho's for more details) Hookers often fall into this category, which is why this phrase came to be.
Anything pertaining to something so attractive or generally awesome, it produces the overwhelming urge to masturbate. Usually on the spot.
"Jesus! Did you see the rack on Jama? Totally beat bait."
"Dude, respect. Your girl is beat bait."
"OMFG! The new Radeon! 1700 shader units? Beat bait."