I'm cool off that
You're not interested in any of the cool stuff people are passing around. It could be weed, alcohol, snacks, or anything you can share.
I'm cool off that, I just ate a whole cake and I'm still happy.
I'm cool off that, I just took a hit and I'm still stoned.
I'm cool off that, I just drank a whole soda and I'm still full.
xs