Free IPhone add on Mobile Device

Lately every time I go on Audiogon Discussion Forum from my Android phone, as I begin scrolling through responses to topics an add for a new IPhone (You have won a new phone) pops up and the only way to get out of the screen is to shut off my phone. Has anyone else encountered this? And is there a work around?
I get this, too, sometimes. I close the browser and reopen it. (Double-click the home button and swipe the browser closed.)
I also get this same type of message for an app, tapatalk, if I remember the name correctly. Same action to close.