Which ones can you think of?
Probably the most famous would be Y&R's Stolen Sperm Saga, which slithered around for about a year and involved leading ladies cat fighting over sperm. It didn't go over so swimmingly with the soap press and fans to this day gag when they think of it.
Another one I remember is on B&B when Deacon was paralyzed and Bridget was giving him physical therapy. It gave him a boner which they both celebrated. Personally I liked it and found it pretty titillating but it was definitely awkward.