Gooch Throb is a condition that results from extreme excitement whereby the male's gooch becomes swollen and red, and a slight throbbing can be felt internally in the region of the gooch.

Gooch throb is not sexual excitement which would result in an erection (see boner or hard on) it is only possible to have Gooch throb in a non-sexual situation.

Briefly, "the realization that each random passerby is living a life as vivid and complex as your own." Originally from the Dictionary of Obscure Sorrows, which has a lot more beautiful neologism definitions like this you might enjoy.