It's worse than that.
Your brain is frantically testing and rejecting conversational gambits and then they say something to which you could reply in a fantastically witty fashion and you miss it and you end up saying "Errrrm, yeah, I quite like cheese."
(wellgroomedwookiee is a filthy-minded hobgoblin, Tue 23 Nov 2010, 15:02, 1 reply, 15 years ago)

Or you say something and start laughing
and realise, almost in slow mo, you can feel the ha-ha - ha falling out of your mouth whilst your brain jumps up and down frantically trying to get your attention, saying 'it really wasn't that funny. Or funny at all. Now would be a good time to stop laughing'
(berk, Tue 23 Nov 2010, 15:07, Reply)

or the awful speaking at the same time
and doing the stopping/starting thing, until you're both left with nothing to say except smile awkwardly
( Amberl was stripey and dominated Europe, Tue 23 Nov 2010, 15:10, Reply)

I rarely get that
but the inappropriate laughing and/or inappropriate talking of bollocks, oh definitely.
(berk, Tue 23 Nov 2010, 15:13, Reply)