You'll look like an idiot no matter how much "experience" you have had (unless you did a surg path heavy psf with lots of autonomy, then you may not look as much like an idiot, but you still will for the most part). Its not surprising that you didn't do much grossing on your electives; when I had visiting med students with me I would show (and let them do) appys, gallbags, and placentas. I would show them how to gross in a breast ca, colon ca, etc but would not let them do it (for obvious reasons). After 2 days OTJ, you'll be fairly proficient with these specimens (with the exception of a really f'd placenta). Don't worry about it--no one expects you to know anything re: grossing, so take a damn vacation already.