How to secretly buy makeup at Target?

I'm 13 years old. I love makeup. I am obsessed with it. I'm going to live with my dad this year, and he puts the foot DOWN on makeup. I still have some, since my mom allows me, but my dad does not let me wear it. I put it on in my room, and experiment still, but I can not leave the house with anything.

So I really want an eye lash curler, Sonia Kashuk brushes, and a NYX eye shadow palette. I could go to the store, but my dad would be coming to check on me in 10 min. I am going to use my keys to open the box, since it has like foundation and concealer brushes etc.

My dad wont notice because he doesn't care for makeup, and I already have what he thinks "a lot" go check my other question if you want to know, because I'm too tired to write it on here.

But if I open it in the bathroom at Target, will people think I am stealing it? If they call my dad I will be in So much trouble. I can't open it at Barnes and Noble's since it is in the food court and like 3 min. Away. It has too be at Target.

What do I do? Plus give me tips on what I need to bring, and how to not be nervous. I get scared the adults judge me, but I know they won't refuse sale. So how to open the box, plus what to bring, plus how not to be nervous.
Added (1). *If they call the security, my dad will be So mad.
Added (2). Sorry I wrote foundation, XD I meant Eye Shadow.

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