Posted by Karl on August 13, 2005
Variations on "to gross out," as for example, "When the other cockroaches ate that one squashed cockroach ... that really grossed me out."
The expression is still heard in its figurative sense occasionally, and was endemic in the U.S. during the 1960s and 1970s. Hasty searches of this site and the Web at large didn't turn up anything, but I believe it originated in aviation. Pilots have for decades used "grossed out" to mean that an airplane is loaded to its maximum allowable gross weight; "bulked out" means that it's packed full, but below max gross weight. Freight dogs flying for FedEx, UPS and DHL still use the terms in their original sense, usually without irony or double entendre.
Given the sudden appearance of "grossed out" in its figurative sense during the 1960s, I suspect that it evolved among Vietnam-era aviators, who then brought it home with them. The meaning could have made the transition fairly easily, from being literally too heavy to lift off the tarmac, to being overwhelmed by events or circumstances, to being merely repulsed by something disgusting.
As an aside, surface freighters - land and sea - have probably used the terms "grossed out" and "bulked out" (or something like them) for a much longer time, but the return of large numbers of military aviators from Vietnam seems to have been the trigger for the rise of the metaphorical "grossed out."