How to handle farting?

No joke. Every time I have one particular 7th grade class, the same hour every morning, there's almost without fail a farting incident. I suspect there's one kid in particular who is the culprit, but I've asked him to do his best to use the bathroom when he starts noticing he needs to fart, and it happened yet again today.

When it happens, the reactions from other students are noisy, they physically move and cover their noses, and it disrupts the entire flow of class.

There's no serious way to address the problem, because they'll all just fall over themselves in fits of giggles.

What do I do?

EDIT: Thank you everyone for the ideas, the laughs, and suggestions! I am grateful for such a great community of teachers.