The point at which you realise that you're saying some important stuff, but also that with the next sip of your cocktail or beer, you will dissolve into incoherence. Example: I was at the cusp of defining the eternal journalist/PR problem at Soho House last night when I realised I was about to join the drunk pile in the far corner. I was near terminal verbosity.
TERMINAL VERBOSITY
Meaning of TERMINAL VERBOSITY in English
Slang English vocab. Английский сленговый словарь. 2012