This is a reference - used by mothers- to refer to the common periwinkle (a type of shellfish, resembling a small snail, and commonly found on shores in the northern hemisphere) and how much the contents of the shell resemble a little boys penis.
‘Kevin, don’t forget to give your winkle a good shake after you’ve had a wee-wee!’
To intend to take a short nap, but end up sleeping for a much longer period. Refers to the story of Rip Van Winkle who fell asleep for a hundred years.
I meant to take a quick nap before my next class but I ended up ripping a van winkle and missing my midterm.