A form of non-penetrative sex in which the male partner (or the top in cases of gay sex) puts his penis between the other's thighs and thrusts to create friction.
Good for bitchy virgin girlfriends who don't wanna do anal and faint at the thought of blowjobs. Also, it makes you sound smart.
"But baby, I'm not ready yeeeet!"
"Fuck, FINE, we'll just do the intracrural!"