There are three Egyptian hieroglyphs depicting penises, each with Unicode characters: ?? ? Amazingly, no-one seems to know about them despite their being among the most succinct and obviously useful glyphs in the standard. The RealRevK reports:
They are rather innocuously named U+130B8: EGYPTIAN HIEROGLYPH D052, U+130B9: EGYPTIAN HIEROGLYPH D052A, and U+130BA: EGYPTIAN HIEROGLYPH D053.
I cannot actually work out what the middle one is meant to be doing, to be honest. Looks painful.
Someone will no doubt explain to me that in fact that is not what the hieroglyph is and that I just have a dirty mind, but if that were true, why are they apparently censored in some fonts?
Many unicode characters fail to attract use simply because they aren't present in any common fonts. The penis unicode characters render for me on MacOS Mojave Firefox and Safari, but disappear in Chrome. Are you seeing it on your system? Are they missing or conspicuosly "censored"? Tell us in the comments!
UPDATE: WordPress's "Tags" panel automatically bowdlerizes a single penis by turning it into the ? emoji, but left dual penises unmolested.