'Mr. Xcitement' off of They Might Be Giants' Mink Car is one of the most heinous things I have ever heard. There's a handful of TMBG songs I don't really care for, but that one is just an atrocity. By far the worst.
And I may or may not catch shit for this, but I'm not particularly fond of R.E.M.'s 'Stand'. A good number of R.E.M.'s more popular singles are novelty songs, but I think 'Stand' is just too dumb to be as well-liked as it is.
I kinda agree with HG re: Stand. Most of their singles I enjoy to some extent (Losing My Religion being a prime example of one that I don't think is stellar but I still enjoy). Even Orange Crush is a better song IMHO.
For me it would be "Shiny Happy People" by R.E.M.. They are my second favourite band, I pretty much love every album in their entirety, hell, I even enjoy The B-52's, but this song song is just plain irritating.