Each week of 2017 we present an English idiom.
“to top it off”: used to introduce the last event in a series of events; usually the series of events and the final event are negative
Example 1: My plane was late, my luggage was lost, and to top it off, my laptop stopped working in the middle of my presentation.
Example 2: And to top off a day that had been bad enough already, his car got a flat tyre on his way home.