it means that you are "excited" or as in you want to have sex like REAL BAD!!!! and its actually spelled horny. Try looking up things on urbandictionary.com :)
It means you feel sexually aroused. This is perfectly normal for people of ALL ages irregardless of sexual orientation, relationship status and sexual experience.
you have orgasms all the time and want sex sex sex like conner Allen cuz he wanks every morning he is banging mate and rebecca Patrick goes out with him mmm.... i can just imagine. im so horney now.