Ouch Ziggy, I totally feel you, just today I had dinner with my folks and my gf... my parents have been attending Tango lessons for about a year or so and they do more than fine, people clapped them at my bro's wedding about a month ago... well, the subject came upon the table and as we were invited to attend lessons with them, I ran in my best Limbo to the restrooms. I think I got away from this one.
Still, take it as a fun experience instead of a mission. And I second the idea of an "encouraging drink".
best of luck!