The sound you make/words you say when you imagine/think about one of two things:
- a particularly sumptuous article of food,
- getting some action with a particularly hot and sexy individual.
Or just a general phrase
to use when you are at a loss
--not so much in an awkward situation
but just bored
. Also pronounced "humina humina", and may be substituted for "hubba hubba
" depending on the context and situation.