Mary-Kate Olsen's Superbad date

Mary-Kate Olsen went on a secret date with 'Superbad' actor Jonah Hill.

The 22-year-old actress, who is believed to be in a relationship with artist Nate Lowman, was reportedly seen with Jonah at Los Angeles' Chateau Marmont Hotel last week.

A source told the National Enquirer magazine: "It was a shock to see Mary-Kate together with, of all people, geeky Jonah. They were on a double date with another couple, dining at the hotel around 10 pm.

"Mary-Kate and Jonah sat close together and seemed totally into each other. They were both wearing plaid shirts that almost matched. It was the cutest thing.

"From what I saw, Mary-Kate had forgotten about Nate and seemed totally enamoured with Jonah. And he couldn't keep his eyes off her, either."

It has also been claimed Jonah was overheard telling his friend, actor Jason Segal, he had asked 'The Wackness' star on a date and she had agreed.

Mary-Kate - who previously dated the late Heath Ledger - went to a Radiohead concert with boyfriend Nate the night before she was seen with Jonah.