"How long will testing take?" — giving estimates without digging your own grave
You blurt out "two days" in three seconds, and that number then lives for weeks — and gets used against you. A first-person take: why test estimation is a special genre (you're estimating the quality of someone else's work that doesn't exist yet), an estimate as a forecast with assumptions, decomposition instead of a single number, three points instead of one, a named buffer instead of "×2 just in case", and what to say when your time gets cut.