United States

Perhaps your friends in NY can locate some open mic events.
Enjoy your stay.

Try this link for starters.

http://folkmusic.about.com/od/tipsforpros/qt/NYC_OpenMic.htm

Get on the "Village Voice" website and look for open mics. The V.V. was the 'go to' newspaper (it's free) for NY's music and artist scene when I lived there. You can also find jams in Central Park (there are outdoor musicians playing everyday), if you have a battery powered amp, and you can also try Washington Square Park, which was my favorite, it's near NY University. When I lived up that way, musicians were allowed to play in the streets for tips. But things do change so you better make sure you don't need a permit nowadays. I'll be spending next month up there and hope to get some playing in. Have fun.