Another sort of oral sex, however this implies a partner licking the other partner's anal area. A highly microbial area, so hygiene is very important when practicing this to avoid infections. Most dangerous bacteria that can be encountered in that area is Escherichia Coli, and you do not mess with an infection with that "bug".

Even if this sexual act is practiced a lot, it is still a taboo subject and always handles barriers when talked about it.

Can be found in other different semantic forms like analingus or rimming, so next time when you hear this terms you know what's all about.