Patrick Stewart kisses Conan O'Brien on 'Conan'

LOS ANGELES, Aug. 18 (UPI) -- Patrick Stewart delighted fans by kissing Conan O'Brien on Monday's episode of Conan.

The 75-year-old English actor gave the 52-year-old American late-night host a big smooch after O'Brien commented on Stewart's recent kiss with longtime friend and X-Men co-star Ian McKellen at the London premiere of Mr. Holmes.

"I knew what I was doing, [but] it took Ian by surprise," the actor said of the red carpet lip-lock. "We are very good friends and quite intimate friends ... I did [initiate it] because it seemed appropriate and that is how we greet one another or say goodbye."

"Ian isn't the only one," he jokingly added. "I don't want you to think I am a one-man guy ... I think I'd go for Sir Sean [Connery]. Maybe a bit of tongue there. [I am] entirely [comfortable kissing men,] but I don't do it with strangers."

Stewart and McKellen portray Professor Xavier and Magneto in the X-Men film series, and recently collaborated on a Broadway production of Waiting for Godot. The former has been married to 36-year-old American singer Sunny Ozell since September 2013.