I was spontaneously given a spliff by a WG once while she gave me a blow job, and it was amazing. But generally speaking I find taking drugs of any sort (including alcohol) interferes with my ability to reliably enjoy a punt, especially if it's with a relative stranger. It works better if you know each other (have been on weed, coke or booze in my ten plus years of punting), but nowadays I don't generally indulge unless offered; in fact I rather like to go on a punt after a big night out instead of during one, as sex chases away the fumes of a come-down quite nicely. Pot sex is something I would do with a GF more than a WG.