With day game you should go from shock to comfort.
So whilst I advise against opening with something like that as a fair few girls will hear the word "porn" and run a mile. Yes girls watch Porn but they also watch ALOT of TV about creepy guys and people that use the word porn = DANGEROUS!!! you can still open with it and then switch to comfort THEN you can recall it later when the comfort is built.
Example:
You: Are you watching porn on your phone.
Her: No <insert offended statement>
You: My bad, I just wanted to get your attention. <AFC statement but converts "are you watching porn" from creepy to alpha.
Her: Oh...
You: Come for a 5 minute coffee with me.
*Go for coffee, build comfort, kino and such*
Her: Okay well I best be going.
You: Whats your number?
*gives number*
You: Sweet, now you can text me instead of watching porn
Her: <inaudible amount of giggiling>