obsexing
You're so obsessed with the idea of having sex with someone that you can't think about anything else. It's like your brain is stuck on a single track.
I was eating pizza and thought about my crush. I dropped my pizza and it was everywhere.
I told my crush I was going to the park. I went to the park and sat on a bench and stared at the sky.
I saw a dog and thought it was my crush. I said hello to it.