I Love Lucy "Lucy Does a TV Commerical" was originally aired Season 1 as Episode 30 on May 5th, 1952.
Little Ricky's birthday party is planned for the same day as Stevie Appleby's birthday party, and Stevie's got all the kids' interest by having a clown and lots of other sources of entertainment. Lucy ends up getting Carolyn to change the date of Stevie's party, because she's going to have Superman be at Little Ricky's party! When Superman can't show up, Lucy dresses up like Superman herself and almost gets herself killed by walking the window ledge from a vacant apartment (where she was changing into her costume) to her own apartment. But Superman does show up and saves the day, including Lucy!