it basically means like when someone is constantly bothering u or always looking in ur direction and makes it RLLY obvious, thus meaning they're obsessed with u abt something.
Friend 1: 'Do u see Theo looking over at us?'
Friend 2: 'Yuh, I wonder how long he's been staring for..?'
Friend 3: 'Y'all I can smell the obsession coming from him, he clearly has a thing for us.'
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Obsessed person: 'Hey, how are u?'
Friend 1: 'u already asked us that five times today...but, I'm still fine.'
*Obsessed person leaves*
Friend 3: 'Yeah i smell the obsession he has with u friend 1'