Makes me horny, with energy supplied by the meth to go fuck like animals.
I find that GHB takes the edge off the paranioa/fidgety-ness meth causes, relaxes me abit. I usually take the meth first, and about one hour or so into tweeking I have some G, when I do it.
I reckon if having the G first the meth might overtake the G, since it has stronger effects. Just from experience.