The act of regurgitating regurgitated substances ie vomiting vomit back into somebody's mouth. To swallow someone's vomit and then puke it back into their mouth. Can go on ad-infinitum until the full cycle is done.
See "Two girls, one cup/finger"
Please note, a throat laundry would not appear on the high street but if it did, it would be managed by Dot Rotten.