Can anyone help me identify a prop...

http://img256.imageshack.us/img256/5616/mug01ac6.jpg

http://img173.imageshack.us/img173/6306/mug02tj8.jpg

I own this mug. It was given to me by Neil Patrick Harris...its signed to me by Neil and Alyson Hannigan. A friend recognized the mug from the above picture so I realized it was not just a cute gift from Neil...it was most likely used in the show. So can someone actually tell me if it was used in the show, and the name of the episode it appeared in.

Thanks in advance

Patrick