I guess Sally is no longer fast if she is ingesting gbl.
Surely you must know a way to mask the taste...just drink it with something that will take your mind off the gbl.
Sweet, sour, salty, acidic any beverage will do.
In regards to thin & thick: Are you certain the 'G' refers to GBL? If someone gave me G id assume it was GHB
However, i have no experience with either substance.