Flip your text upside down and backwards. Paste it into a bio, post or message.
Each letter is swapped for a Unicode character that looks like its flipped version, and the whole string is reversed. The result is plain text you can paste anywhere that accepts Unicode, like social bios and posts.
On most modern apps and browsers, yes. A few platforms with limited fonts may render a couple of characters as boxes, but the common letters and digits work almost everywhere.
No. It is real Unicode characters, not a font, so it survives copy-paste into places that do not let you change fonts at all.