I foolishly put my "Tervis" type (rigid) straw in the dishwasher. When I pulled it out it was no longer straight. To fix it (straighten) the straw back, I put 2 metal kabob skewers inside the straw and ran it back through the dishwasher. The skewers held the straw straight when the plastic was heated up.
Now I need to remember to handwash the straw!
Metal Kabob Skewer