Costello was an amateur boxer.

During his teenage years, Costello fought in the ring as an amateur boxer named Lou King. However, the kid's dreams were dashed when his father unexpectedly showed up to a fight with a family member and recognized his son in the ring. Costello's mother put her foot down the next morning at breakfast when she found out.

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Abbott may have been kidnapped.

The later teenage years of Abbott are a mystery, as there aren't many accounts as to what he was up to during that time. However, one account suggests the boy was kidnapped and taken to Norway. Abbott eventually returned to the United States to become a cashier at a casino.

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Costello had a partner before Abbott.

Could you imagine watching Williams and Costello? Before Costello paired up with his eventual partner, he teamed up with a man named Al Williams. However, Williams died of a heart attack after performing only a few shows together with Costello. 

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The duo had quite an age difference.

While most people think of the duo as peers, Costello was actually nine years younger than Abbott (11 years, depending on sources). The pair didn't meet until they were in their 30s.

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Costello had to change his voice.

After several appearances on radio programs, including The Kate Smith Hour, Abbott and Costello were told by producers one of them had to change their voice. Apparently, they sounded too similar and listeners couldn't distinguish between the two men. That's when Costello adopted the higher pitch, for which he became known in his later years. 

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They had to lie about their most famous bit.

One of the producers of The Kate Smith Hour didn't like the "Who's on First?" bit after watching Abbott and Costello perform it at a theater. The only way for them to get it on the show, however, was to lie about not having any new material for the week. Because the duo was such a big ratings draw, the producers suggested they try out their baseball sketch to fill time. In reality, Abbott and Costello planned this bluff, and saw this as their chance to introduce "Who's on First?" to a wider audience.

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They were instant hits in Hollywood.

The duo was first featured in the film One Night in the Tropics. Originally a bit part in the film, the duo provided so much good material that the lines of others actors had to be cut in order to meet the 90-minute requirement. Although the film was a flop, Abbott and Costello were a hit with audiences in their supporting roles. 

Image: Universal Pictures

Costello made more money than Abbott.

Once the duo arrived in Hollywood, Abbot and Costello earned a 50/50 split of the profits. However, Costello, being the comedian, felt he should earn more than Abbot, the straight man. Eventually, tension reached a peak when Costello threatened to break up the act if Abbott wouldn't settle for a 60/40 split.

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They supported the war effort.

Abbott and Costello were tapped by the U.S. government to raise money for the war effort. The duo toured the country extensively, and even performed in a family's backyard after a kid and his friends raised several hundred dollars.

Image: Associated Press 

Costello performed on the radio the night his child died.

Costello's infant son died in a tragic accident shortly before his first birthday. Embodying the phrase "the show must go on," Costello performed that night on The Abbott and Costello Show, with Abbott giving a touching statement shortly after the show wrapped. 

Image: Orphaned Entertainment

The duo's relationship was strained towards the end of their career.

It's something we hate hearing about our favorite entertainers — that they don't get along with their costars. Unfortunately, that was the case for Abbott and Costello. Although the two were completely professional on camera, tensions mounted until they didn't speak to each other towards the end of their time together. The duo eventually broke up in 1957.