Jafo, you must be a bitter, angry person for wanting to punish people so severely for joking. It's just absurd what you want.
I'm all for people taking responsibility for their actions, and if that means a bit of prison time, then so be it. However, the punishment should fit the crime and not go over the top for an act of stupidity in which noone was harmed. Whether this girl or her friend tweeted this message, 10 years is an over-the-top kneejerk reaction and is just as silly as the tweet in question.
What I'd like to see is perpetrators of violent crimes, where people are hurt, tortured, raped, actually serve out their sentences and have no chance of parole after just a few years of being a 'model prisoner' All too often rapists reoffend while on parole after serving just 5 or 6 years of a 12 - 15 year sentence, and that's just wrong. Parole for serial sex offenders should never be an option. In fact, it should be mandatory that all sex offenders are castrated, as well as serving the full sentence handed down by the court... and that sentence should be no less than 15 - 20 years, or more, depending on the severity of the offence.
So yes, it is fair enough to be angry regarding crime, but that anger needs to be proportionate to the crime. Therefore, to suggest that some silly little girl gets 10 years for a stupid tweet, while a rapist gets just 5 years for violating another person physically and emotionally, is completely off balance and not proportionate to the crime.