Astoundingly, the answer is ... possibly. Doing so would require a particularly strong crusher and would be more likely to crack, rather than grape-like pop, the skull of the crushee. (Also: SPOILERS FOR TV SHOWS at the link.)

http://feeds.boingboing.net/~r/boingboing/iBag/~3/kqXM3EN6nwQ/can-a-human-crush-another-huma.html