Used in casual contexts among friends or in informal settings, not in professional environments. Just finished the marathon, I'm gagging for a burger.
Pro Tip 2/3
Intensity of Need
Expresses a very strong desire, more intense than just wanting something. I'm gagging for a holiday, haven't had one in ages.
Pro Tip 3/3
Potential Misuse
Avoid using in formal contexts where its casual nature can be misinterpreted as unprofessional. In a business meeting, don't say you're 'gagging for a deal'—it's too informal.