Baka to Test to Shoukanjuu: Matsuri - Sentaku ni Yotte Tenkai ga Kawaru "LIPS Eizou"

A promotional video that was shown to the public at Comiket 78, and uploaded to YouTube and posted on the official website. It was also included with the first Blu-ray/DVD volume of the Matsuri OVA.

It is done in the style of a visual novel game played on a Nintendo DS screen.

(Source: AniDB)