420-Friendly
"420" in a dating bio is cannabis-culture shorthand: the poster uses cannabis, or is at minimum comfortable around it.
Written alone rather than as "420-friendly," "420" in a dating bio carries the same general cannabis-compatibility signal but leans more toward a direct self-identifier -- "I use" -- than the softer, explicitly-tolerant framing "friendly" adds. In practice the two are often used loosely and near-interchangeably by daters, and neither app UIs nor mainstream dating-advice sources draw a hard, universally agreed line between them; this entry states that overlap plainly rather than inventing a precise rule that doesn't exist in real usage. The number itself predates dating apps by decades. It traces to 1971 in San Rafael, California, where a group of high school students calling themselves the "Waldos" agreed to meet at 4:20 p.m. to search for an abandoned cannabis crop; the meetup never succeeded, but "420" stuck as their private code word for cannabis and later spread through Grateful Dead touring culture into wider use. April 20 (4/20) subsequently became an informal, unofficial cannabis-culture holiday marked by public gatherings, and "4:20" itself is sometimes still referenced as a daily time associated with cannabis use. That broader cultural weight, more than any dating-specific coinage, is why the bare numeral reads as self-identification: it is the same code cannabis culture has used for itself since the 1970s, just relocated onto a dating profile. Because the numeral has no built-in "friendly" softening, it appears more often in bios written by people who use cannabis themselves than in bios written by non-users signaling tolerance -- though, as above, this is an observed tendency in how the term is used, not a fixed rule enforced anywhere.