I was gonna answer that ... but being a relative noobie, I"m glad someone else did (and said what I was thinking).
While at my desk I try to do some 2 hand squeezes too ... they aren't the best, but it's better than nothing. And as Asanon stated, I take every opportunity to stretch the lil guy. Many times I opt for the stall as opposed to the urinal so I can give him more than 1 min of attention (not too long or co-workers will think I'm jerking it)