Vocabulary.co.il has just added a new game to their site called the "Slang Game." It focuses on English idioms and slang phrases. I'm thinking it might also work well with a Smartboard, although I couldn't speak from personal experience on that.
If you aren't familiar with the site, it is a website of free vocabulary games that are especially helpful for ESL/EFL students. The Slang Game is on the front page.
Vocabulary.co.il link
New Game For Teaching Slang/Idioms
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