I'm generally perceived as a pretty funny guy, I joke around with both my reports and those I report to, and, yes, even with customers all the time. I've found that I don't need to diminish others to do this, there's plenty of other crap to joke about, like the quality of our products, how long it takes to get stuff done, the UX of the tools we share, dumb programming trends. It's easy to laugh without it being at the expense of others.