For example, browsers used to actually allow pop-up windows (as in it would open a new desktop window (not a tab), sometimes off-screen). And then when you closed it the browser would let it spawn more pages.
There was a common pattern of spamming popup windows with a "close" button the same place a "run" button was when you downloaded an executable in Windows 95.
And then after closing 10 windows with the button in the same place they'd hit you with an executable download.
This was common.