British actress Emma Watson arrives for the world premiere of "Harry Potter and the Half Blood Prince" at Leicester Square in London July 7, 2009. [Agencies]?

Emma Watson was terrified of laughing during her kissing scene with Rupert Grint.

The 'Harry Potter' actress battled through an urge to burst into giggles when she kissed Rupert Grint for the finale of the wizard film franchise and considers the scene to be one of the movie's most comedic moments.

"It was awkward for both of us because we are like siblings - imagine growing up with someone since you were nine.

"It's strange, but I think Rupert and I both really enjoy doing comedy and getting the chance to do that because a lot of the film is so dark and really serious."

The 19-year-old British starlet - who plays the role of Hermione Granger - recently filmed her final scenes with Rupert for the last wizard movie, 'Harry Potter and the Deathly Hallows'.

Emma says it was nerve-wracking to lock lips with Rupert - who plays Ron Weasley - on camera.

She explained: "We broke the ice by both of us confessing just how nervous we were about doing it, and because we were both in exactly the same boat, we felt exactly the same way about doing it. It was a relief to know we were both going through the same thing.

"The kiss is the finale. I don't want to give too much away... I don't want to ruin it."