Really yummy food that is incredibly nang.
The person eating the delicious food may say "om nom nom" as they eat to show how much they are enjoying it.
"Om nom nom, that food was nomtastic!"
"Oh wow Becky! Your cakes were nomtastic!"
"Becky always makes nomtastic food"
When something tastes so good it feels like you are having an orgasm.
The first known occurrence of this phenomenon came spreading jam over a "stripy strip", wrapping it around a cube of chocolate and dipping the whole thing in sherbert.