Underdog - Season 3 - Eps 20: Simon Says 'Be My Valentine', Part 4
Polly pulls the handcuffs off of the pole and cries over her now-paper hero. Then she hears the familiar saying, "The secret compartment of my ring I fill with an Underdog energy vitamin pill." She sees Underdog is flat but all right. She finds a flat energy pill in the ring and when she give it to him he breaks out of the Valentine, takes the handcuffs off her hand and they fly to City Hall. There, Underdog saves the mayor and stuffs Simon, Cad and the two henchmen in the machine. Polly turns them into Valentines.
About Underdog

Title: Underdog
First Air Date: 1964-10-03
Last Air Date: 2000-02-01
Status: Ended
Rating: 6.2/10 (from 22 votes)
Language: EN
Seasons: 4
Total Episodes: 125
Network: NBC
Genres: Animation, Comedy
Production Companies: Total Television Productions, Leonardo Productions
Synopsis
Underdog is an American animated television series that debuted October 3, 1964, on the NBC network under the primary sponsorship of General Mills, and continued in syndication until 1973, for a run of 124 episodes. Underdog, Shoeshine Boy's heroic alter-ego, appeared whenever love interest Sweet Polly Purebred was being victimized by such villains as Simon Bar Sinister or Riff Raff. Underdog nearly always speaks in rhyme, as in, "There's no need to fear, Underdog is here!" His voice was supplied by Wally Cox.
Cast

Wally Cox

Sandy Becker

Kenny Delmar

George S. Irving

Mort Marshall

Norma MacMillan

Delo States

Ben Stone

Allen Swift