I had that happen on my 390 Adventure with the stock TKC70's right after a rain.Thanks. Yep it was wild, had the cruise on at 70mph on a perfectly straight road and all of a sudden my back wheel is coming around.
Just rolling along casually at 65 mph and the back end started coming around on me.
Luckily, I didn't have my ear plugs in so I heard the motor spin up and was able to get off the throttle before it got weird.
So much for traction control...