Thisbeautiful moment, courtesy of Betelgeuse, when he realizes Melinda additionally messed with his memories of Lydia's name, not just hers of his shortly after figuring out there's been a misunderstanding between him and Danny:
Danny was then treated to a very colorful and descriptive tirade that would've been censored heavily even to qualify for an R rated film. The Ghost With The Most seemed determined to use every curse in existence in the most creative manner possible. Danny thought he might have stopped speaking modern English at one point and either switched languages or started using something older. Or both. It was actually pretty educational.
Say It Again
We see how the journal conversations got started, and how Lydia's exasperation morphs into amusement.
When Lydia tells her classmates a thinly-disguised ghost story version of Betelgeuse's existence, he contributes to the atmosphere by making the air colder and dramatically knocking out the lights. Even she has to laugh about it afterward, sarcastically calling him "a real menace to society."