I've done it with April Cox and ... IT IS AWESOME!
It's a grown-up version of a "slip-n-slide" and a thousand times more fun. Yes - it's foreplay and it got me so wound up I was reduced to a begging, blithering idiot. Well, that's me normally ... but you get the point!
Like a stripper slide.
The gel is like magic ... it's really not as messy as it sounds and it will eventually dry on your body and you won't notice it ... until you take a shower ... then it reconstitutes. So you need to shower afterwards.
Oh and - TIP the girl - the gel is pretty expensive stuff!