When you need something resolved to move to the next step but you need the next step resolved to fix the first step. Rinse and repeat
Quality Assurance Team: “Hey Team, can you look at this bug I found? It’s blocking all testing.
Team: We’re busy right now but can you test this new stuff?
Quality Assurance Team: Not until you fix the old stuff.
Team: But the new stuff fixes the old stuff
Quality Assurance Team: But we can’t test the old stuff to then test the new stuff! This a real merry-go-fail