In the 2011 movie David Tennant played Las Vegas showman and vampire expert Peter Vincent.
In this video Charley (Anton Yelchin) tries to talk to Peter about strategies for vampire-killing. It also contains the famous leather trousers adjustment!
Warning this video contains strong language and the video is short in accordance with the copyright holder's wishes.
Apologies if this video does not play in your country. Many thanks to the YouTube account Just Tennant for uploading the video.
Fright Night section of DavidTennantOnTwitter.com