title_body: What does rolling/swirling a hefeweizen actually do?
upvoted_answer: A proper hefeweizen is an unfiltered beer. The yeast and other sediment that would be filtered out for other brews is left in. These particles tend to accumulate on the bottom of the bottle during storage.
  
  By swirling the the beer in the bottle you're suspending that yeast and sediment so it can be poured into your glass. This is what gives hefeweizens their fruity (banana?) flavor.