Teller cut it off and Penn was fine with that.
Penn Jillette says he was moved when the granddaughter of an employee at the Las Vegas hotel where he and Teller do their show began chemotherapy for cancer.
So, he had 10 inches of his ponytail cut off and donated to Locks of Love.
That's an organization that provides wigs to underprivileged kids with cancer who've lost their hair because of chemo.
Penn says he's had a long ponytail for 25 years.
Now he has a little stub of a ponytail.