-- Taylor Swift's "Shake It Off" is definitely a song that gets stuck in your head and you find yourself singing without even knowing it.
But to be singing the song while sitting right next to her -- that's a different story, but that's exactly what happened to actor Justin Long.
"At one point they were playing that song," Long told HuffPost Live about sitting next to Swift at a Knicks game earlier this week. "That song, you all know it and I think had been playing over the speakers. It's one of those songs that really gets in your head, really crawls in there."
"And of course she heard it," he added. "And she was like, 'Oh,' and sort of started laughing, and I was so embarrassed."
He said it just got in his head and he didn't even realize.
"I didn't do it so she would hear me. I wouldn't have done it had I been all that conscious of all that," he said.
But, in the end, Long said Swift was really sweet about it and was actually grateful.