Okay, I'm going to go ahead and say this since I forgot to mention it anywhere on my ask page before now. Unless it appears in the Comics for Fionna and Cake and/or on this ask page
I didn't actually participate in it.
There are a few exceptions, like some things having to do with the Mushroom War, but yeah.
So no, I have never had sex with Bubba, especialy not in a shower. (Do you know how hard that would be anyways? He's gum and shower sex is hard as heck.)
That may apply to someone elses canon of their blog though, so try one where me and Bubba are dating since on here that isn't taking place at this time.