I always thought it was:
A SMN, WHM, and RDM are sitting in a bar.
The WHMs glass is low so the WHM says, "Refresh plz."
The RDM proceeds to cast refresh on the WHM's glass.
The SMN points toward his glass and motions for a refresh.
The RDM uses convert and blasts the SMN to smitherins with Fire II.
Ghey, but that's the way I heard it :-þ