The brief but heavy periods of sleep which commonly accompany the use of the benzodiazepine alprazolam, a.k.a. Xanax.
If you don't get much sleep at night and decide to take a little Xanax the next day to 'relax', you can expect to be taking a Xanap very shortly afterwards.
Often employed by white hats of low moral fortitude to get into the pants of unsuspecting young women. These men, incidentally, should be killed with anthrax for their utter fucktardation.
Frat Boy A: Dude, what happened to those chicks we brought home from the bar?
Frat Boy B: They're still in the car taking Xanaps, you sneaky serial date rapist, you!
(high five, followed by unrequited homosexual thoughts)