My team recently migrated from ClearCase to Git. Some team members are accustomed to hijacking files, which in ClearCase means making private changes to a tracked file, changes that you don't intend to share with anyone.
ClearCase basically ignores such files when doing the equivalent of a Git add/commit, and won't overwrite them when doing the equivalent of Git pull.
Is there an equivalent in Git?
Note I'm not saying this is a good workflow, even in the ClearCase world. The answer to "why would you want to" is that it's what they're used to.