The Allergy Problem is an episode of Peg + Cat (TV series).
It begins with Peg and Cat in the garden, picking clovers. One of them is a four-leaf one so Peg puts it in her hat for good luck. Peg is sneezing a lot, and sometimes she sneezes before being able to finish a sentence. When this happens, Cat finishes the sentence. They then get a phone call from the doctor, who states that Peg is probably allergic to something. This worries Peg as the doctor said that cats are a possible thing she's allergic to.
While Peg takes a bath, Cat (who is wearing a necklace made out of clovers) sits outside and sings a blues song about how he's sad that Peg might be allergic to him, and then a bird takes him away.
When Peg is done in the bath, she goes outside and notices Cat is not there. This makes her sad. Then, Ramone shows up in a special plane that runs on 100 pebbles and when the dial reaches 100, that means they need to put more pebbles in. They sing a song about looking for Cat and missing him, then they land in a shallow part of the ocean because it has run out of pebbles. Peg puts seashells in the fuel tank, thinking they are pebbles. Ramone thinks it won't work, but it turns out that they do work and they fill the tank up with 100 seashells. They try to set off again but a whale swallows them.
Luckily, they are not being digested, and they have found Cat. Peg reassures him that she will still be his best friend even if she is allergic to him. The whale is allergic to something, so it sneezes them out and they fly home.
At home, Peg sniffs four of the objects in her hat, but neither of them make her sneeze, and she falsely believes that's it because she knows there are five objects in there and she miscalculated and thought that two plus two equaled five. However, when she realizes that it was a mistake and that two plus two makes four, not five, Peg sniffs the four-leaf-clover and it makes her sneeze. It turns out that she is allergic to clovers, not cats. The bird and the whale from before then show up to apologize. It turns out that they only took Cat away and swallowed Peg, Cat and Ramone by accident.
They then go back in time and ask various historical figures if they have ever made mistakes and sing a song about mistakes.