Always be sure to squeeze your balls between sets.
In my recent evaluation, the female evaluator told me I did just fine except for one thing--I needed to squeeze my balls before each set and before I handed them to the players...
Now that I have somewhat recovered from one of the most embarrassing moments of my life, I agree but its not something I would tell anyone else.
And who says officiating isn't fun?
(Hopefully noone will be offended by this post--but then, many a truth is said in jest.)