See how the Urban Dictionary defined a Yoruba Demon

The term Yoruba demon has come to stay and is associated with guys from the western part of Nigeria(Yoruba) who break women's hearts or are serial cheats.
Well, the Urban dictionary has it's own definition with a name as an example. It reads

A Nigerian guy (Yoruba) who goes after a young lady's heart with no intention of loving her. They are typically met at parties, and would mostly wear white agbada (clothing).
They sometimes are seen in groups.
Oladimeji is a known yoruba demon.

via Loud Naija Media