My sister gets so horny when she’s ovulating, but refuses to…

My sister gets so horny when she’s ovulating, but refuses to take her tights off, convinced she isn’t having sex (and can’t get pregnant) if she’s still “fully dressed.”  I’m allowed to do anything I want to her, so long as the tights stay on… Usually we just play a bit until we both come, but recently I bought her a special part of durable, stretchy tights instead of the usual ones we use… 

So, tonight I’m gonna stretch them until they’re wrapped around my entire cock, swallowed up inside her tight teen pussy… and once my stocking-wrapped cock is finally positioned right against the divot of my little sister’s virgin cervix I’m going to unleash the most powerful orgasm I’ve ever had… no little mesh of fabric will prevent me from impregnating my sister’s eager, waiting eggs.