What (who) is chub-rub - definition

Dry rub; Butt rub; Espresso rub; Rub (food)

chub-rub

This is generally only experienced by the overweight and slightly-overweight people. chub-rub is a heat rash in the inner-thigh/arse/crotch region caused by the friction and sweat produced by walking or running in the heat.
Hurts like a bitch, but that's what you get for having tree-trunks for legs.
I can't go out to Sweetwaters with my friends tonight because i have a severe case of chub-rub and I can't walk!

Chest rub

TOPICAL TREATMENT FOR DISCOMFORT APPLIED TO CHEST

Cold rub; Vapor rub; Chest vapor rub

Chest rub, cold rub, or vapor/vapour rub is a mentholated topical petroleum jelly-based ointment intended to assist with minor medical conditions that temporarily impair breathing, including the common cold. It is applied to the chest, often immediately before sleeping.

https://en.wikipedia.org/wiki/Chest_rub

Pericardial friction rub

A pericardial friction rub, also pericardial rub, is an audible medical sign used in the diagnosis of pericarditis. Upon auscultation, this sign is an extra heart sound of to-and-fro character, typically with three components, two systolic and one diastolic.

https://en.wikipedia.org/wiki/Pericardial_friction_rub

Wikipedia

Spice rub

Spice rub is any mixture of ground spices that is made to be rubbed on raw food before the food is cooked. The spice rub forms a coating on the food. The food can be marinated in the spice rub for some time for the flavors to incorporate into the food, or it can be cooked immediately after it is coated in the rub. The spice rub can be left on or partially removed before cooking.

Rubs are typically applied as a powder, aka "dry." Some "wet" rubs may have oil, water, or other liquid added to make a thick paste.

https://en.wikipedia.org/wiki/Spice rub