A.P.
My son hated it at first too; then we found him a fun electric toothbrush that looks like a firetruck and lights up. This was over a year ago now, and the novelty has worn off, but it got us past the initial reluctance and now he's no trouble. (we've replaced the batteries in it several times and go back to it for a change -- he likes to mix it up now with toothbrushes that have his favorite characters on them!). The making funny faces and noises that someone else mentioned helped, too!