I do remember reading an NTSB report a few years ago about cabin crew announcements and particularly the safety demonstration. I cannot locate the document at the moment but I will be sure to post a link when I do. The report suggested that when the demo is done in a light-hearted and/or slightly comical way, pax are more likely to a) pay attention and b) remember the content.
I would agree that perhaps DJ is a little out-of-the-ordinary in this regard and that sometimes the jokes may not be to everyone's taste and even that at 0800 on a Monday morning they may be a little irritating. Having said that, I was on a BNE-CNS recently and the CS delivered not only the demo but every PA with jokes in it (btw, with a perfect deadpan that made it even funnier) and received a round of applause from the cabin upon her last PA as we were arriving in CNS. If one thing can be said, it does show that the pax were listening for once.