We (family) agree. There is nothing more intimidating than scoring and then walking away like you do it all the time. Celebrations make it seem like a big deal. Handshakes or shoulder-slaps are fine. Just make it seem like it's not a big deal. What do you have to be excited about? Maybe if it's your first TD or some special occasion or record, shake your fist or something, jump up and down a couple of times. But if it's just a TD or an INT or punt return for a TD, hand the ball to the ref and walk away, maybe shake some hands or high-five. It should be a natural thing, and if you do it a few times, the other team thinks so too. I think if I saw a team that didn't celebrate all season, but still had fun, that would be scary as hell. Like, "oh, crap, we're gonna get beat" scary, not like, "too fat to leave the house" scary.