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1.
The act of French kissing, when one partner expects to use tongue and finds the recipient maintains an open mouth without any tongue interaction.
She would have been the girl of my dreams if only she didn't 'cave mouth'.
by NGK June 01, 2011
 
2.
Effectively what should be 'french kissing', only one partner declines to use any tongue. Leaving the other to find theirs inside an empty void.
The girl was damn hot but when we kissed she totally gave me 'cave mouth'.
by TheWrestle June 12, 2011