Sometimes it’s useful to be able to find GUIDs in your project – especially when a previous Sitecore partner has hard-coded GUIDs in various user controls and classes throughout the site.

Anyway, the regex to run in Visual studio is:
[0-9A-F]{8}-[0-9A-F]{4}-[0-9A-F]{4}-[0-9A-F]{4}-[0-9A-F]{12}