Sandra Bullock began laughing hysterically when her son chanted German while at lunch with Matthew McConaughey.

The actress is mother to two-year-old Louis, who she plans to raise to have a keen interest in languages. Sandra's mother Helga who died in 2000 was a German opera singer and the actress is keen to ensure Louis knows all about her.

She has already been teaching the tot some German words, which Louis showed off during a recent day out. He began chanting, "Quiet please!" in the language as Sandra chatted to fellow star Matthew, much to her amusement.

"Matthew thought it was just baby-talk, but Sandra was in hysterics. She knows her mother was smiling down on the funny incident as well," an insider told National Enquirer.

Louis has also been overheard telling photographers not to take pictures in German.

Sandra, 47, plans to enrol him in a French speaking school when he is old enough so he is multi-lingual.

"[He can't join] until he's three, so for now she's looking to hire a French-speaking nanny and handling his German education herself," the source added.