In India, the number 420 is slang (char sau bees) for a fraudster or someone dishonest.
The slang comes from the Indian Penal Code, Section 420, which deals with cheating, and was likely popularised by the Indian cinema with movies such as Shri 420 and various others where dodgy characters were referred to as 420.
The maximum punishment awarded under this section is imprisonment for a term of 7 years and a fine.
Section 420 also exists in the penal codes of Pakistan, Myanmar, and Bangladesh.
This is because the penal codes of these countries inherited from the Indian Penal Code of 1860 instituted by the colonial government of British India.
Globally also, 420 doesn’t seem to have any socially acceptable connotations.
420, i.e., 4/20 = April 20, is when pot smokers worldwide come together to smoke pot.
Legend has it that in the early 1970s, some kids at a high school in San Rafael, California, got together at 4:20 (after school) to smoke pot.
The ritual grew in popularity, and eventually, 420 became a code for smoking marijuana.
Soon, 420 was converted into 4/20 for calendar purposes, and the marijuana day or weed day was born.
