Answer: popupads

AnswerCrossword Clue
POPUPADSSurfer's hindrance
POPUPADSThey're often blocked
POPUPADSOnline annoyances
POPUPADSBlockers' targets
POPUPADSWeb annoyances
POPUPADSWeb surfers' annoyances
POPUPADSInternet annoyances
POPUPADSBrowser bothers