I was sopping wet from ear to ear when my girl requested nattilingus. Without missing a beat, I grabbed my freshly cracked Natty off the nightstand and started pouring. She shivvered hard from the cold and I almost drowned.
Dude, she was fuckin' wild last night, she started liking me everywhere and started to go down but she was so drunk that she gave me navalingus instead.
This is different than a rimjob. A rimjob would, however, be a precursor to anilingus. It is the act of plunging one's tongue into the anal cavity of your sexual partner and then swirling and thrusting aforementioned tongue in an effort to make said partner happy.
It is well advised to wash the anus that is to be pleasured thoroughly (and perhaps even douche) before attempting this.
Anilingus is the "scientific" term for applying ones mouth to another ones asshole. Then plunging ones tongue deep within the anal cavity, and swirling it 'round; giving one's partner sexual pleasure.