In Fallout, it is found out that some iguana bits are actually human flesh bought from Doc Morbid in Junktown. These are sold at a discount, and appear as chunks-on-a-stick instead of an actual iguana-on-a-stick.
In Fallout and Fallout 2, it is possible to feed Dogmeat some iguana-on-a-stick to keep him as a companion.
References
↑Bob's Iguana Bits is very well established in 2161, when Fallout takes place. Therefore this is likely time frame for the business's operation.