How to Greatly Annoy Somebody

Disappearing Ink

So I would always get those stupid things from school that's all like "Sell this many things of whatever and you can get this prize!"
Well one time I decided to actually sell some stuff for the school because it was for something that I actually cared about, band. So after selling some tubs of cookie dough to my family members I managed to receive a prize. Disappearing ink.
Now, at the time, I wasn't overly excited about this because I was a kid and so were my siblings but after a while my older sister started to care about looking nice and it was finally time to strike.
I hadn't thought about this little tube of disappearing ink since elementary school but my dad was getting rather annoyed about this closet in our basement that held anything and everything from our childhood. I was the one child in our three child home that had the task of cleaning out said closet but I found some pretty cool stuff as well as my ink.
So anyways, now that my sister (let's call her Eggplant) wants to look nice and actually have people like her and whatever it was the perfect time to mess with her. I used up quite a bit of this disappearing ink, after using it on my stuff first to make sure that it wouldn't actually mess up all of her clothes, on her wardrobe and then the rest went onto her bed.
Well, when she saw what happened she freaked out, it was one of the funniest things that I had ever seen. I didn't want to be too mean so I showed her how to get rid of it but it was still quite the prank and definitely annoyed her.

And a side note - This can also be in the form of a pen.

Have fun lovelies,
Megan and Bobbi :()