To "snail it" is to drive your car really slowly, like a snail, through the stop sign intersection, without ever actually stopping the car. It can also just be called "snailing".
"That stop sign on 25th comes up so fast off of Western, I can never *actually* stop at that thing! So I just usually snail it, and I'm fine."
"Yeah man, I snail it way too much. Finally got pulled over for it the other day."