OBSESSION
hung up (on someone or something)
obsessed with someone or something; devoted to someone or something .(Slang.)John is really hung up on Mary.She's hung up, too. See how she smiles at him.
bug
n. an obsession or urge.I've got this bug about making money.I have a bug that causes me to eat tons of pasta.
hang-up
n. a problem or concern; an obsession.She's got some serious hangups about cats.I don't have any hangups at all. Well, almost none.
happy
mod. obsessed with something. (A combining form showing a strong interest in the thing that is named before happy.)All those guys are girl-happy at this age.Pete's car-happy right now. That's all he thinks about.
have something on the brain
tr. to be obsessed with something. (Have got can replace have.)You've just got girls on the brain, you silly twit.I have money on the brain, I guess.
one-track mind
n. a (person's) mind obsessed with only one thing.When it comes to food, Tom has a one-track mind.Mary has a one-track mind. All she thinks about is Tom.
stuck on someone or something
mod. enamored with someone or something; obsessed with someone or something.Tom is stuck on himself—as conceited as can be.I'm really stuck on this stuff. It's just yummy.
wrapped up (in someone or something)
mod. concerned or obsessed with someone or something.Sally is pretty wrapped up in herself.I'm too wrapped up in my charity work to get a job.