Needed a small cone (10mm) cone spanner to tighten the freshly adjusted brakes on a housemate's BSO. All my normal pliers were way too thick so I looked in the toolroll and noticed my chainlink pliers. Thin enough to fit and capable of enough grip to let me lock the outer nut against the inner.
Win.
Ah, never forget that Bicycle Shaped Objects require a specialist item, namely the Tool Shaped Object:

Yup. I was convinced I had one of those in the first toolkit I bought when I got a hybrid about 6 or 7 years ago. Can I find it?
Oh no. Not a chance until I really don't need it.
On the other hand in my tool roll is a set of 12 Park Tool spanners. On my bikes the only thing I could undo with them is the hydraulic lines on the brakes. Thats one 8mm spanner needed. I only use the 10mm spanner for the brakes on other peoples bikes. Why do I have 12 spanners? How drunk was I browsing Amazon that night?