United Kingdom, April 24 -- Brenda Song and Macaulay Culkin's "pettiest" fights are always over Mario Kart.

The 38-year-old actress revealed she and the Home Alone star, 45, are both "very, very competitive" when it comes to the classic Nintendo racing game, and they get "mildly mad" about how things go down.

During the new episode of Cosmo Goes Deep, Brenda's Running Point co-star Kate Hudson asked: "What's the pettiest thing you and your partner fight over?"

Brenda admitted: "One thing that we can argue about is we do play Mario Kart sometimes, like, in bed.

"And then we get very, very competitive and we will like get like mildly mad at each other, for like cutting me off or like winning, beating me last minute.

"That's probably th...