Heff
From jugglingpatterns
A heff is a double thrown as a column to the same hand. In other words: this is the throw that you repeat in the 4-club fountain.
Trivia: There are two people who claim that they coined the term because they wanted some short name for the throw.
I personally suspect, as double-turn columns thrown in passing patterns tend to go forwards towards the other passer, that it evolved naturally from everyone saying "Can I heff it back, please".