Re: this has been bothering me
This has been well summed up. As long as it's only in your head, you cannot get into trouble. Just keep it there.
It's understandable that you'd be a bit dismayed by these fantasies as they're not what you'd consider to be typically arousing. So, if you're into this, you might want to think about what exactly it is about these things that arouses you. That way, you can better understand what tension is being relieved by masturbating to them, as masturbation reduces sexual tension,the fantasy gives a clue about what the sexual tension is about.