In front of 1,000+ people (EDIT: I recently found out it was more than 2,000!)
With my Brony shirt on.

Yeah, it was a great day for me; I had no idea they'd call me up for the talent show.
My dad was in it singing a song titled How He Loves Us, then after everyone cheered (including me), he was asked about his family and stuff, then he was asked if anyone else in the family played a musical instrument.
He said that I played piano, and people started urging me to play, so I did.

I played Border of Life from Touhou 7.
I don't know the exact keys for it since I can't read sheet music, but here it is.
After this, a brony named John came up to me and asked me where I got the shirt.
He was the only other brony I met on this cruise.