Taking a shower, while high on crystal meth. A typical user will begin to experience symptoms of Obsessive Compulsive Disorder (OCD) and thereafter feel a desperate need to clean themselves.
I had been up for 3 days dude, but then I went in for a quick methrinse, to help me wake up!
Can be male or female, but esp. the latter. A 'Rinser' is a spunk-lover who removes your condom, stretches it, and squeezes the spunk out into her gob, gargles, then swallows.