This is an old trick,it was possible on Cabal EU some time ago like 6months ago,almost all scammers was from Germany so...start to search em
From what i know that is just a picture,the scammer use an UCH but you see it like a Bike or whatever he wants or when you and him press OK on trade an auto flooder starts what create the lag/scam when your OK is done and his not so *OK* because is that *lag*,he gets your items and you get nothing back from him