Colleagues talk gibberish at me?

I constantly go to work tired n in the office one particular colleague keep saying weird nonsensical stuff at me whenever I pass him by. It's like he's greeting by saying some weird stuff like ur a winner bobby or I'll see u in vegas n i have no idea how to even respond to this. I've beem doing bad at my job sales so it feels a lot like he's mocking me but I can't tell at all. Any ideas?