"I have never been quite sure whether this is the worst opening move [1. g4] or whether that dubious title belongs to 1 f3. At least after 1 f3 d5 White can play 2 f4, or after 1 f3 e5 2 e4 Bc5 3 f4!?, but 1 g4 gives no such opportunity. One of the best ways to manhandle this miserable move is to play a sharp gambit against it." - Raymond Keene.
http://www.chessgames.com/perl/chessgame?gid=1026281
It's almost as strong as 2.Qh5
Which isn't saying much. In fact, I would rather play 1.e4 e5 2.Qh5 any day over the Grob. As bad as both openings are, the Parham isn't completely dumb, because White can give Black a somewhat awkward position to play, even if Black should be better. The Grob, on the other hand, is not good whatsoever. To repeat what I said in a different thread about the Grob: "The Grob is an amateur's blitz weapon at absolute best (and other openings do a better job and are more sound), and just plain bad at worst."