In an orgy or threesome, to lick the union and environs of people having penetrative penile sex. This may be done by laying below a pair having doggy style sex, or in front of a pair in reverse cowgirl, or any other acrobatic means one might imagine. The point is that the genitals, the taint, asshole, and usually the cock and balls all get some oral attention. Not related to the bisexual panda we all love.
While John fucked Mary's ass while she bounced in his lap, their bi friend Steve was on his knees between their legs happily licking John's shaft and Mary's taint, performing a noisy, wet, lingling.