Delegating a job to a junior mechanic prior to a test flight only to note that you have lost half the engine oil on the left engine and upon opening the window getting doused with hot engine oil. Securing the engine and flying back to base on the other engine over water at night.
Same situation where the junior mechanic forgot to install the nose gear scissors bolt and having to get out and install it while the idiot pilot decides to do an engine run-up while I was in the nose gear compartment. I'll never cum that way again.
Now my most stressful situation is walking down the stairs without falling.