How Do I Get Back At My Sister Who Went On My Computer?

[Banana]

I just found out that my 16 year-old sister went on my computer at about 3PM yesterday and fucked with all of my stuff. She went on my facebook, my twitter, my spotify, but what pissed me off the most is that she read all of the messages that I've sent/been sent from/to girls. She always goes on my facebook if I leave it for 5 minutes at my dad's, and I've had enough.

I want to seriously get back at her. Enough so that she doesn't do it again.

On my cousin's birthday we had a party, and whilst my cousin was out buying food for the party, we turned everything in his room upside-down. I thought this was an amazing prank and I think I might try it.

Although, it's a lot of work for one person, and I want to know if anyone has something better. Help!

[Y U Act Entitled?]

"Enough so that she does't do it again", well... you can prevent this by "locking" the computer when you go to the bathroom or wherever you went. Make a profile on the computer, and add a password to the profile, that means you need to type in a password to get onto the account... and when you "lock" the computer, that means to "unlock it" you need to type the password in again.