slowy or slowie is usually a word used to describe people who are dumb or thick or are a bit slow

when you're hungover as shit after a spending a night drunk as a skunk

or slowie is a blowjob. This term used by Graduates of Strath Haven High School from about 2000-2003?4, perhaps extending a few years before graduates of 2000.

When you’re friend ir spouse is asleep (you may have drugged them with sleeping pills) and you suck their dick. Sleep + blowy = slowy. It has to be consensual.