Sharon Horgan knows how to write a good sex joke. While many people consider Catastrophe a romantic comedy, Horgan said that she refers to it as a “sex comedy,” or if you’re Carrie Fisher, who plays Sharon’s mother-in-law, Mia, on the show, “a funny porn.” “I think it’s very hard not to write a sex joke,” Horgan said during a conversation moderated by Vulture’s own E. Alex Jung at the Catastrophe panel at Tribeca’s Tune In event on Tuesday. “The thing is for them to feel real and not corny.” Another thing that should seem real? Prop boners!

After watching a clip from the second season where married couple Rob and Sharon fight while Rob sports a boner, Horgan said, “It’s hard to give a man a pretend boner because they’re like, That looks really, not quite big enough. They don’t want just a little prop boner.” Horgan then recalled an episode of her series Pulling where she ran into a similar problem. “There’s this scene where my ex-fiancé spirals into a depression [and] tries to hang himself and when you asphyxiate you have an erection. He was hanging from the ceiling and I come in and try and help him cause he’s changed his mind and right beside my face is a boner. We had a lot of arguments about the size of that boner.”

So how did they decide what the right size was? Horgan said, “I think we just go for reality. We didn’t want it to be too boing boing boing but we wanted people to see it!”