This worked because DiMaggio was remarkably shrewd when it came to his autograph. He'd happily sign a ball or piece of paper for anyone who asked, but he absolutely refused to sign bats except at special events. That made a DiMaggio-autographed bat extremely rare, allowing him to charge whatever the hell he wanted to sign one (generally a few hundred thousand dollars per appearance). We assume Joe used one such bat to tattoo Paul Simon for not paying for the use of his name in "Mrs. Robinson."
Neil Armstrong will be forever remembered as the first man to walk on the moon (and is likely the only person to do so that any of us can actually name). However, back in the 1960s, he was just an astronaut earning nowhere near enough money to pay for the life insurance he needed to support his family in the (very) likely event that he and his crewmates got superkilled by a space explosion.
That exact phrase was in the back of his mind when this photo was taken.
While locked in isolation for a month leading up to their mission, Armstrong and his crew came up with the most brilliantly cynical idea in the history of time -- they signed hundreds of autographs. Anything space-related they could find, they signed, and then had the items sent to a friend to be dropped in the mail on the exact date of their moon mission, July 16, 1969. That way, in case they all died in the callous vacuum of space, their families would be able to sell the bejeebus out of their autographs (which would be postmarked the very day of their spectacular deaths). Because nothing opens wallets quite like tragedy.
Karl Smallwood's signature isn't worth shit, but his name is funny. You should probably point that out to him on Twitter. Because no one ever does that.