You'd Better Believe It! is an expression of affirmation and agreement. The crossword solutions for this term are FACT (4 letters), DOGMA (5 letters), DOI (3 letters), ISM (3 letters), TENET (5 letters), IDIDSO (6 letters), and NOFOOLING (9 letters). A FACT is a statement that can be proven to be true. DOGMA is a set of beliefs or principles that are accepted as true without proof. DOI stands for 'Doing It Ourselves' and is a term used to describe self-reliance. An ISM is a belief, principle, or ideology. A TENET is a principle or belief that is held to be true. IDIDSO stands for 'I Did It So Others Can Too' and is a phrase used to encourage others to take action. Finally, NOFOOLING is an expression of certainty and assurance.