Lost in Translation

[tfifiny]

Ok, so as an intermediate knitter, I got a bit lost on a pattern a friend gave me before she went out of town... Searching online hasn't found me any help in figureing out this stitch...
The pattern goes.. k1, yo, *sl 1, k2tog, psso, ... etc.
I get stuck on the psso (pass slip stitch over) and can't find any more than that. WHAT do I do?

[Jan in CA]

You slip one stitch, knit 2 together and pass the slipped stitch over the k2tog. It's a double decrease.