Fruiting fungus.
After all, the true body of fungus lies below the ground. The mushroom is the fruiting body, literally just a disposable reproductive organ. Not even analogous to a penis, more like the cum glob that contains the sperm.
Although that means its not really one Fluffy. Fungus isn’t reproductive with merely two genders, they need interaction with many others. How many depends on species, but some are the “40 genders and counting” kind.
That’s more like Skettitty than anything else.