Conor McGregor spent most of the time at his Mayweather fight after-party locked in a conversation with Irish soccer legend Robbie Keane

So, when we saw Robbie in Bev Hills this week we had to ask -- what did you guys talk about?! 

Keane wasn't down to spill all the tea -- but admitted they talked about "everything."

We asked about the nature of their friendship -- Keane said they're both from Dublin.

Bottom line -- Keane's a big fan and says Conor's "gonna do great things."

[h/t Chamatkar Sandhu]