Why the drug tests?

wrote the following:

So aperantly my moms drug testing me. Big waste of money concidering I'm NOT SMOKING! However with my "better off dead" luck I will come out positive... Because when my boyfriend and our friends smoke I'm normally around them. Let's just thank god she fell asleep last night and frogot to do the test cause I was out drinking. Thankyou lord for cutting me SOME slack. However your love for me doesn't seem so great when I get into more trouble when I'm behaving but then when I'm being bad my mother leaves me the hell alone? Her wasting money on this drug test means I'll have to be asking people for lunch money all of next week... Good job mom. Great parenting. I see how well you trust your parenting.(: