I guess it's already been proven that it was in fact McLovin, but here's my anecdote:
I live in Toronto, Canada and I was walking in a very chic part of town when I noticed McLovin and I walking directly towards each other. The street was strangely empty so it was just him and I. I'm not into the celebrity scene at all, but I definatly wanted to make sure it was him just so I could tell people later that night that "I saw McLovin". He's probably had enough of people calling him McLovin ever since Superbad, so he was careful to keep his head down (he was basically staring at the sidewalk as he was walking by me) and I noticed he was sporting a RED SOX baseball cap. I thought to myself, McLovin is a fan of the Red Sox? Anyways, just as we walked by each other I said "McLovin?" and he picked up his head and gave me a little smirk. It was hilarious.