Someone's open-mouth chewing, and I must scream

If you don’t burp, loosen your pants and sigh loudly after eating, you might as well slap the chef’s mom

Is slapping the chefs mom not customary? No wonder I get kicked out

Misophonia IS a disorder since it implies an EXTREME abnormal reaction to certain sounds. Anyone can be made uncomfortable by certain sounds, just like anyone can become uncomfortable by being locked in a closet or seeing pictures of the deep, dark ocean, but people with misophonia will tend to have a reaction along the lines of triggering fight or flight response which they tend to have trouble resisting action upon.