Because this is a tourist town, the Vietnamese tend not to advertise their more weird culinary tastes, but we found one last night which, in addition to "normal" fare, offered pig's brains, pig's ears. jellyfish stew (which, even if I were not allergic, would not be on my list) and silkworm salad.  I could see Calvin's eyes light up but we settled for roast suckling pig and duck curry.   But I have a feeling, he will want to return to sample some of their more esoteric delights.