head of cattle
When getting head for a friend and just as you are about to cum you pull as hard as you can on the back of their head so as to ramrod them and yell moooooooo mooooooo. It is best if done like the cow being branded on the Family Guy hit TV show.
Derin was giving me a BJ and just as I was about to bust a nut I gave her the ole head of cattle. Moooooooo mooooo.