Saying someone is ridiculously goodlooking, that you cannot believe the high ranking on the attractivness scale this person/item/song/etc has been able to achieve.
Telling someone they are embarassed by a romantic gesture that has been offered to them
;Telling someone that they look the best they can possibly look at the moment
You're so hot right now in those vintage jeans.
I think I'm in love with you (giggle), you're so hot right now!
Short-hand for the word floccinaucinihilipilification, meaning the estimation of something as valueless (encountered mainly as an example of one of the longest words in the English language).