Fog was one of the rare Bobs songs that you'd hear yelled out as a request at concerts, but usually never performed, since it really was Gunnar's, and he left the group in 1991. Gunnar's signature tune Helmet was also a popular request yet not performed by the remaining Bobs for a very long time, but Joe Bob Finetti finally started doing the song live and he pretty much made it his. I gotta admit, however, no one can holler it like Gunnar.
The difference between Fog and Helmet is that you can listen to Helmet on the Bobs' album My, I'm Large; Welcome to My Fog never actually went on an album (though it did show up on the Bobs/ISO video but that was hard to get for a long time. I think you could also get a live version of it on tape if you were part of the FOBS fan club a long time back, but I'm not sure.) Now you can hear Fog online, albeit with backing instruments, but all the voices singing along are strictly Gunnar's. He mentions on his website that the Bobs never released Fog on an album because they weren't able to get a satisfactory studio version.
The Bobs have since performed Fog onstage; Richard taught Amy Bob her part onstage during a show at the Somerville Theater a few years back. But since I haven't seen them perform recently, I'm not sure if it made its way onto their regular program. It did make a lot of fans in the audience pretty damn happy that evening, that's for sure.
The funny thing about Gunnar's album with Fog on it, well, it's a kid's album. (His label G-Spot Records changes its name slyly to Gee, Spot! Records when he releases a kid's album.) Fog is open to several interpretations, not the least of which is one involving heavy fogs of oddly bittersweet-smelling smoke (witness the lines When I go for a drive I feel lucky to be alive / The air feels so good coming off of the hood / And I don't go very fast, I want it to last / And strangely enough, it does) Take that as you will.