It's not a euphemism, it's the rule of thumb I used to determine if I expected myself to be productive during that time, and therefore, if I should track that time. Eventually I decided I just wanted all the data and started tracking everything. The main difference is that I started tracking how much time I was asleep. Even before then, I tracked some things while I wasn't wearing pants (like showering or being on my laptop in bed), and I didn't track some things I did while I was wearing pants.

People typically think that "wearing pants" is a euphemism; I should change how I communicate that, but it's still how I think about it.