Nick Cannon was in the home to see his ex-wife Mariah Carey depart her mark on Rihanna‘s breast … and he says extra girls ought to observe their lead.

We acquired Nick heading in to do some charity work Friday on the Los Angeles Mission and our photog requested him concerning the viral video from Mariah’s current live performance.

Nick says watching Mariah autograph RiRi’s boob was “sizzling” … and he hopes it turns into a development.

On a extra severe be aware, Nick says it was actually nice of Mariah to depart the stage to go and greet Rihanna through the present … and he provides RiRi some love for exhibiting assist for MC.

Nick’s giving again to the group right here for the vacations, and we additionally requested him what it is wish to play Santa Claus for all of his children, together with the twins he shares with Mariah.