1. Eccentric Posh men with loud voices. You know the ones, Tom Baker in Little Britain (and in the old Lee and Herring radio show that he also did the voice-overs for, which has been repeated recently, on BBC7); Chris Morris' character in The I.T. Crowd, and his supposed nephew, who took over his business, after he committed suicide; a couple of the characters from Roman's Empire; and, of course, the voice-over bloke, from the E4 adverts.
2. Smart-arse, young, American fat blokes, who have a snappy answer for everything. Jack Black is the prototype, but there have been many since he first found fame. The two that have been on T.V. recently, are the main character's friend, on that new show Reaper, and the one sitting in the office cubicle, on that advert for godaddy.com
3. Comedy Raps. The latest is on an advert for Pot Noodles. Surely they've been done enough, already. Talk about lazy writing.