The Mystery of the Disappearing Pens

I'm a Mom with three kids.  And my kids seem to think that if I have something, then they can take it whenever they want to.  For example, I can not for the life of me keep an ink pen.  I start off with tons of them and I keep them on my desk so I have one within reach when I'm on the computer.

 
But every time I reach for one, they are all gone.  Where do they all go?  The kids will come and ask to "borrow" one, and I answer, "you can borrow it, but BRING IT BACK."  But they never do.  And when I ask where it is, they always say "I don't know." 

The next thing I know, I'm down to three ink pens on my desk.  So I guard them like a hawk.  One of the kids will borrow one and I watch them to make sure they don't lose it.  I start asking them every two minutes, "Are you done with my pen yet?"  They invariably roll their eyes at me and swear on their cell phones that they will return it.  Then I take my eyes off of them for a second and POOF!  the ink pen is gone.  And no one knows where it went.  So now I'm down to two ink pens.  

So I tell myself that I need to be even more vigilant.  I can't let anymore of my ink pens disappear.  I tell myself that I won't let the kids borrow them anymore.  But they're kids, they like to draw, they like to write.  And it's good for them.  So I can't bring myself to say no when they ask to borrow one.  "MAKE SURE YOU BRING IT BACK!"  I tell them.  And, as usual, they promise.  I resume my eagle eyed surveillance of them.  Each time they put it down, I ask if they are done with it.  "No Mom.  I'm still using it."  is the answer I get.  So I sit and watch them.  And I swear, even with me staring right at them watching that ink pen, it STILL DISAPPEARS!  And now I am down to one ink pen.

  
So now I am being fanatically possessive of this one lonely ink pen on my desk.  One of the kids comes up and says, "Mom can I..."  "NO!"  I interrupt before they can even ask.  "I only have one pen left.  You can't have it."  

The thing is though, I have absolutely no idea what they do with all of my pens.  Are they eating them?  Where do they go?  I've checked the couch cushions, under the couch, under their beds, and there are no pens.  In fact, we just spent the weekend Spring cleaning.  We cleaned out closets and everything.  But we didn't find any ink pens.  I'm starting to think that there is a portal hole some where in my house that leads to another dimension.  

And guess what?  In the time it took me to write this little story, my last pen has disappeared.  It was right here beside me a second ago.  I didn't even see any of the kids reach over and take it...