When one is under the influence of hallucinogenic substances and is thinking so fast or unclearly that they cannot maintain a steady stream of though. The act of losing the thought previous is called the upshift.
What was i talking about? I totally just upshifted.
upshift: define #2
(verb) A transitional moment during doggy-style or sex from behind when a male moves his erection from the vagina and inserts it in the anus.
“Why was she so upset at breakfast this morning?”
“Well, she is still pissed about me upshifting her last night. I guess it hurt really bad. Oops.”