You shouldn't write in other people's diaries.
Ali is at Kamryn's house when she sees Kamryn's diary sitting next to her bed.
Ali wants to play a prank on Kamryn.
When Kamryn goes to the bathroom, Ali uses lipstick to make kissy lips on Kamryn's mirror.
"When Kamryn goes to the bathroom, Ali opens up Kamryn's diary, reads a few pages, and then writes ""Ali was here"" on the next empty page."
Kamryn laughs when she sees the lip print on the mirror.
Kamryn is mortified that night when she realizes that Ali had looked in her diary.