They key word there is the last one; "job"
Being a charter captain and operating in a professional manner, of course one would not pull pranks on their customers.
However, my crews are comprised of my friends... and usually people I've been friends with for years if not decades. We make fun of and prank each other incessantly. A little jovial, completely harmless "hazing" is to be expected. It's starting to be that the former noobs who had the pranks pulled on them are now the ones pulling those pranks on the true noobs. Plus, f'em if the can't take a joke <img src="http://www.traveltalkonline.com/forums/images/graemlins/Cheers.gif" alt="" />