From The Archie Show:
Archie (Dallas McKennon), Jughead (Howard Morris), Betty, & Veronica (both voiced by Jane Webb) decide to attend a Riverdale High "Costume Party" as "Martians", but with the simplest of costumes. Reggie (John Erwin), as usual, tries to sabotage his friends' efforts, if only because he wants 1st prize for himself. Kinda reminds you of Daffy Duck in those days, doesn't it?
DreamWorks Classic, which holds the rights to the Filmation era Archie cartoons (1968-78), uploaded this episode to YouTube:
Too bad Reggie didn't want to be a team player, else he'd be spared the humiliation that comes his way.....