Be my bridesmaid
As with wedding planning and its unequal distribution of labor, the respective roles of best man and bridesmaid are slightly out of kilter. There are so many more responsibilities if you’re the bridesmaid than if your friend has asked you to be their best man.
The emotional support alone is enough to put you off, but the organization of the party to end all parties (before the actual wedding) sounds like a full-time job in itself. Oh, and you’ll also have to take out a large loan to be able to afford to do all this stuff. Maybe just politely decline?