My favorite bit of comedy involving athletes will always be the Season 3 episode of The Simpsons entitled Homer at the Bat.
Originally aired on February 20, 1992, the episode featured nine actual Major Leaguers as guest stars, including Darryl Strawberry, Don Mattingly, Roger Clemens, Wade Boggs, Steve Sax, Mike Scioscia, Ozzie Smith, Jose Canseco, and Ken Griffey, Jr.
To many fans, including myself, it still ranks as one of the best Simpsons episodes ever. The basic story is that the Springfield Nuclear Power Plant softball team, led by Homer, advances to the championship game, prior to which Mr. Burns decides to hire ringers to ensure his team's victory.
The episode features such classic situations as Ken Griffey Jr. overdosing on 'Brain Tonic' and declaring "It feels like there's a party in my mouth, and everyone's invited", as well as Mr. Burns pinch-hitting for Darryl Strawberry with Homer, and rationalizing his decision by saying that he's "playing the percentages" (as a left-handed pitcher is on the mound, and Strawberry bats left-handed, while Homer bats right-handed).
I'd really like to show the entire episode here, but I can't, so, just go watch the DVD or catch it in reruns or something. For now, just enjoy Mr. Burns run-in with Don Mattingly's sideburns (a scene written, amazingly, prior to Mattingly's real-life hair run-in with George Steinbrenner).