Jí másùn is a common Yoruba expression and a slang too. Jí másùn is a complete Yoruba statement as short as it is. It is a two worded Yoruba statement that is also a bit of a command.
Jí másùn means, “Wake up, Don’t Sleep.”
Breaking down the expression;
Jí in Yorùbá means “To Wake”,
Má sùn in Yorùbá means “Don’t Sleep”.
So, when you combine them both, you have the full meaning of Jí másùn to be, “Wake up, don’t sleep.”
The expression is very commonly used by Yoruba Afro pop musicians as part of their lyrics in songs where they mix a bit of Yorùbá expressions in their songs. The phrase Ji Masun has also become a slang that Nigerians use playfully with each other to say, “Don’t sleep” or “stay at alert”.