pinging the needle
When one becomes so intoxicated with alcohol that they could not possibly get any more intoxicated without vomiting, or remaining conscious. This is when your internal alcohol tolerance "meter" maxes out, or hits the limiter, thus, "pinging the needle."
"Holy shit, last night I was so sloshed I almost ralphed out the window of the car on the way home, but I just ended up drooling on myself- definately pinging the needle!"