When you have sexual intercourses with a bald guy whose nose is crooked and he cums in your mouth whereafter you spit it over his scalp and rub it all over it. Afterwards you let it dry and scrape it off.
Her: I met this bald dude last night and we did something really weird. I don't know what it was called... Oh and btw. his nose was all crooked
Him: Oh, must have been a "Dirty Statham"