It is very likely the entire reason Woogie not only befriended Ted but became his best friend was to eventually use him to get to Mary. Not only that, but he always resented him because Ted (in Woogie's mind) stole Mary from him. There is also the fact that he never loved his wife and kids.
Dom told Ted to masturbate before his date with Mary because he wanted to sabotage him by making him act un-masculine and platonic while on the date. Alternately, since Dom knew about the zipper incident, he may have also known the part about Ted being Mistaken for Masturbating moments earlier - he was hoping Mary would arrive a little early and catch Ted actually masturbating this time.
