Got Hairballs? ASPCA Offers Tips On National Hairball Awareness Day"It was one of those moments that I usually meet with a series of four letter doozies, but this time, I reacted to the giant grey blob on my couch (which was forming a giant stain) with a resounding Yes!.", said 1010 WINS News Anchor. The last Friday in April marks National Hairball Day. Learn all about your cat's yucky habit in this report.