One who sneaks into the background of a person or group of people posing for a picture, usually making a face or picking their nose, totally unbeknownst to the photographer.
Sometimes, the savvy photo-imposer will even squeeze in with a group of friends posing for a *guest phtographer.
Guy showing off pictures at work- "Here we are in New York, see the Statue of Liberty behind us?"
Co-worker- "Yeah, but whos that guy next to you scratching his nuts?"
Bill: Here we are at Joe's party, what a blast!
Dave: Who the hell is the guy next to you putting his tounge in your ear???
Bill: Damn photo-imposer, Janet said he grabbed her ass during the picture.
somebody who's steppin' their game up and showin' off and showin' out like it ain't been done before
Guy 1: Yo dog, Ricky Rozay stepped onto the scene goin' harder than before!
Guy 2: Yeah, especially when he started doin' collabo's with Trina the Diamond Princess. They bring it hard with the swagg, pushin' Porsches while they poppin tags. They be eatin!
Guy 1: Fo sho, brah, they some real show improvers goin' ham on 'em!