1. An interjection. Expresses frustration, excitement, or surprise.
2. A noun. Describes objects or processes which take too long or too much technical knowledge to describe - often under circumstances warranting the phrase as an interjection.
Use 1. a) Where the heck did you put my keys? Blaffy blooffy!
b) Blaffy blooffy! You scared me, Elsa!
c) I had no idea you would be here! Blaffy Blooffy!
Use 2. a) I went down to the blaffy blooffy to get my taxes done.
b) Jeremy carefully pried the blaffy blooffy from the barbed wire
entanglement and rescued what remained of it.
c) If your blaffy blooffy isn't finished soon, I swear I'll kill you.
d) Come on man. Blaffy blooffy can't be that hard to read; i read 25
pages of it in the bathtub this morning.