Some players -- like the now-immortal Keith Comstock -- pose for them on purpose. Some are semi-tragic mistakes. Others, well, we just don't know.
What we do know: From bat-handle obscenities to boa constrictors and mascot photo bombs, these are 10 of the funniest and most memorable baseball cards ever.
Billy Ripken 1989 Fleer
With perhaps the most famous error card ever produced, Billy Ripken is known to this day as much for the bat handle pictured on his 1989 Fleer card as he is for his career with the Baltimore Orioles or his famous sibling. The words F--- Face were inscribed on Ripken's bat, a mistake that the former infielder has said stems from that being what he wrote on his practice bats to easily distinguish them from his game bats. Fleer issued corrections of the card without the explicit word, including a highly popular white-out edition.
Cal Ripken 1994 Upper Deck
While brother Billy's card claim to fame came courtesy of a Magic Marker and a bat handle, Cal's came via the telephone. While the 1990s Zack Morris-era cellphone looks hilarious today, it was the cool new technology of the time -- and Ripken appears to grasp the importance of taking a mobile call from whomever it is he is talking to when his Upper Deck card was snapped.
Mickey Hatcher 1986 Fleer
There was no question that a Mickey Hatcher giant glove card would make this list, with the tougher choice being which Mickey Hatcher giant glove card to include. In addition to the 1986 Fleer version pictured, Upper Deck released a 1991 version with Hatcher toting a giant glove over his shoulder.
Jay Johnstone 1984 Fleer
Harry Caray was known for being both a Cub Fan and Bud Man, but it was journeyman Jay Johnstone who had the sense of style to rock a Budweiser umbrella for his 1984 Fleer card. It turns out that the umbrella was actually a form of a hat called a "Brockabrella," with Lou Brock as a spokesman, to keep someone dry while still having their hands free.
Glenn Hubbard 1984 Fleer
Ignore for a moment the giant snake draped over Glenn Hubbard's shoulders in his 1984 Fleer card and you still have a pretty amazing shot featuring a Phillie Phanatic photobomb and some other 1980s mascots appearing in the background. Now, back to that giant snake over Hubbard's shoulders. Yes, that is a boa constrictor -- and a reptile that became part of a card famous enough to have its own bobblehead.
Bip Roberts 1996 Score
The beauty of the Bip Roberts sombrero card comes in the mystery of the Bip Roberts sombrero card. Most players on a card on this list at least give a tell that they know they are in on a joke of some kind, but not Bip. Yes, he is sporting the sombrero -- but that look in his eyes is all serious game day.
Oscar Gamble 1976 Topps traded
A card made to commemorate Oscar Gamble's trade from the Cleveland Indians to the New York Yankees became an iconic symbol of the baseball era that encompassed the outfielder's career. Sporting a large Afro that his hat simply couldn't contain and an elite mustache, and announced by the headline "Yankees take Gamble on Oscar" (get it? Gamble ... ), he became a cult baseball hero because of this card alone.
Oscar Azocar 1993 Topps
Oscar Azocar hit only .226 with five home runs over three major league seasons with the Yankees and San Diego Padres, but take one look at this card and there's no doubt that love for his bat was not the reason. In fact, he managed to produce multiple entertaining baseball cards during his short big league career.
Chuck Finley 1994 Upper Deck
During his 17-year major league career, Chuck Finley made five All-Star teams, won 200 games and rocked out guitar-style on a baseball bat at least once.
Rex Hudler 1996 Upper Deck
Rex Hudler is another one of those players with multiple cards that could have earned a spot on this list. But we're giving extra credit for his 1996 Upper Deck issue being one of the rare cards with an entertaining picture on the back -- as evidenced by this shot of him milking a cow in full Angels uniform.