Silent But Deadly

They can be silent but deadly Or even loud and proud It sometimes fills an empty room Or even when there's a crowd It's smell is one you'll recognize For most have smelled it before It's stench is undescribable From beneath the bathroom door It comes when you least expect it But everyone knows it's there The odor is overwhelming We're mostly too sick to care If you think I'm talking 'bout cuttin' the cheese Well, that's not it at all For once again. if you know me, It's just my mother-in-law