You won't truly know your limits until you test them.
In the name of science, last night extensive research was performed; datapoints gathered and documented. Data crunching during Phase 6 (below) and this morning has yielded this handy chart:
1 Drink: Jill smiles and laughs more than usual. Jill is deemed a cheap date. Jill could still use a soldering iron if necessary.
2 Drinks: Jill has a pretty solid buzz. Smiling continues. Room is 6% spinny. Jill finds herself getting many hugs; people seem to think Tipsy Jill is Extra Fun. This is the simple happy fun buzz state. Jill could still be on Jeopardy.
3 Drinks: Jill has a seriously phatty buzz and caution must be exercised to ensure inside-voice thoughts don't become outside-voice utterances. Smiling and happiness abound. Singing becomes easier. (It was a party / cabaret night. Have no fear: I don't just randomly burst into song.) This is reaching the higher limits of the optimal buzz state. At a rockin' party where other guests were partaking in adult beverages and the music was rockin', this would be the level ideally attained.
4 Drinks: Balance skills become slightly jeopardized. From this point, happiness is only maintained if sitting down.
5 Drinks: Balance skills and judgment are impaired; eyes lose focus. However, inside her goofy exterior, Jill is entirely aware of the reality of the situation, and is wise not to put herself in compromising positions. She sits down and observes rather than participates. Conversations are silly. Smiling continues.
6 Drinks: Hurling seems like a good idea. Jill requires a reassuring arm (but doesn't need to be held up by any means) to successfully navigate to the ladies room door. The only way the room is not spinning uncontrollably is when Jill sits in a very uncomfortable postion. Sleeping is imminent. Barfing is considered. Jill sleeps off drunkenness on the deliciously cool floor of the Wilmington Drama League ladies room handi-capable stall. People come in to periodically check, and Jill is able to crack somewhat clever self-depricating jokes. Jill is completely aware of the silliness of the situation, and can't believe that someone of her typical grace and elegance (ha) is now, herself, the embodiment of what she typically likes to lighteartedly ridicule. I overhear that I have been deemed "a very fun drunk." 
AFTERMATH: No hangover whatsoever. The only preventative measures I took upon my arrival at home were: drinking two glasses of water, eating a mini-bagel and taking an Excedrin.
 Brian Elam's going away / birthday party held at WDL. He's moving to my old digs: Tempe, AZ.
 In this case, shots of Sambuca Romana; a favorite.
 Do not taunt Happy Fun Buzz.
 Aim high, kids!
 Yes, I got a ride. :-)