Affirm verb – To state as a fact usually forcefully. Rat on and affirm are semantically related In some cases you can use "Rat on" instead a verb "Affirm".
Rat on verb – To give information (as to the authorities) about another's improper or unlawful activities. Affirm and rat on are semantically related in admit topic. Sometimes you can use "Affirm" instead a verb "Rat on".