rickyt I would probably be P.O'ed also. Don't mind pranks, but messing with a man's tools is a good way to get one's face ripped off, or semi-permanent facial knuckle dents. You can bet if I were him I'd have checked awfully close for any damage to my box and held whoever was responsible in pretty low regard, to put it mildly.
A prank we pulled on a part-timer once was pretty good. His father was a day-turn machinist, and at the time I was on afternoons. The kid worked afternnons also, and at the end of the summer he was ready to go start college. He told us when his last day was, and we, being the goodfella's we were, told him we were throwing him a farewell tailgate party in the lot after work. This was a good number of guys, probably 20-30 or so. Well, we all had a few beers and then 4 or 5 of us grabbed him and each held an arm or a leg, etc. Someone grabbed the roll of cellophane wrap and we proceeded to coccoon him from his shoulders down to his knees, so he couldn't really move much. At that point we laid him face-down over the tailgate/bed of a pickup and yelled out for "Bubba" which was the nickname of one of our welders, a big old 300 pound guy who had a trace of a southern accent. We had planned this for a few weeks, since this kid was kind of an obnoxious prick, and different guys had been telling the kid about how Bubba was a ************ and how he always talked about how the kid was cute and so on. Well anyways here comes Bubba around the side of the pick'em up truck and proceeds to tear a hole in the cello-wrap rigt around this kids rear-end and pretends like he's going to go about doing the you-know-what! You should've heard this kid scream and holler like the dickens! "When my old man finds out about this he's gonna kick ALL your asses!!!" etc. Screeamin' like a little girl, I tell ya'! We took a couple Polaroids too, for keepsakes and all, y'know! Needless to say he was happy to discover it was all a prank, but he was whiter'n a sheet 'til he did, lol. His old man had a rip-roar over that one, I swear I never seen anyone laugh harder'n he did when he learned of it.