For instant gratification, though, Chapter 6 of Broom of the System is probably the funniest chapter I've ever read. It deals with a conversation held in a restaurant next to a glutton that the characters cannot ignore, despite their efforts to concentrate on their own issue.

Get it from the library and give just that chapter a shot. Maybe it will give you enough encouragement to read the whole thing straight through. There aren't that many other hilarious entire chapters from Wallace, but once you feel like you're sharing a humor gene with him, it might work.

Also, getting into his essays might make you feel more in tune with him.