Kimmer, I don't believe Safari's popup blocker allows one to customize it. Ergo, many Safari users (including moi) use
Pith Helmet:
"PithHelmet blocks image, javascript, Flash ads and GIF animations. It can also collapse blocked content so that it is hidden from view. It is fully customizable for a specific site or group of sites and contains a new advanced rule editor in addition to a custom Safari Preferenences pane."
4.7 star rating at VersionTracker, $10.00 shareware.
FWIW, I like it fine and it does a wonderful job, is rock solid, and blocks much more than pop ups, like ads, flash, etc., but I think the interface could be better, e.g., at first the myriad of options and settings can be overwhelming or confusing.
In my old age, anything with more than a five minute learning curve is suspect.
HTH