18 Again!

At his 81st birthday party, an old man (George Burns) closes his eyes and wishes he were 18 again. When he opens his eyes, his wish somehow has been granted: He inhabits his grandson's body, and the grandson (Charlie Schlatter) inhabits his. Comedy ensues as each tries to deal with the other's life -- including the fact that the body switch also means a girlfriend switch! How will they explain the personality changes? (official distributor synopsis)