The term Plotkin is similar to a blumkin, which is when a man is sitting on the toilet taking a shit. And has his woman come in and give him head during the act of shitting.
The major difference is the voracity of the shit. A blumkin is oral sex during a conservative or average shit, a plotkin is oral sex during an aggressive and explosive shit.
"Vlad, get your ass in here and give me a plotkin!, I had del taco!"