This breaks every law of physics.

Is this normal?

I was on my bed, just thinking about if the alarm system went how fast my parents would react. I thought it would be interesting if I Tried it [I was in the phase of half-consciousness during sleep, when you are all dizzy and confused.] Than suddenly, the alarm went off. We live in a extremely safe suburb, and searched the house and there was nothing, and non of us knew why the alarm went off, and now i'm scared shitless.

maybe that your brain was half concious so signals from your ear were telling that alarm went off and then you had a kinda dream thing and then when noise was persistent you woke and "found" your dream come true.
Sarcasm:Or an alien who went to see kangaroos in australia visited your place accidentaly.
(space ships may prove to be annoying sometimes)
:)

What is breaks is all the laws of common sense.

To conclude that thinking about something just once and have it happen excludes all possibilities of coincidence. No laws of physics were broken - just the general rule that something must be repeatable before you start making stupid assumptions.

There are billions of people on Earth who, at every moment of every day, think about stuff that might happen. If some of them occasionally line up with what does happen, then it isn't anything special.

Also... umm.... how, exactly, does this break any law of physics?? (nonetheless all of them...)

It doesn't break any laws of physics. Alarms go off randomly all the time.

Do it again. I bet you can't.