It's not something I do often. It's just sometimes in certain situations without thinking about it.
Some common examples when I use us instead of me is.
"When you're ready, tell us"
"Follow us and I'll show you where it is"
"You hurt me when you say stuff like that. It makes us cry"
(These examples are taken from moments when I thought afterwards. "What the hell are we saying". Yes I use we in my head )
I hide things on myself that I won't need for a week or two, and then I have to look for them (always frustrating) I don't even know why...
Hmm, practicing pickpocketing, sneaking, picking locks and witchcraft when I have spare time for over 10 years now:P The last one might strike a bit odd but even if it doesn't work, it has taught me to meditate and a thing or two about herbs:P