As a child, my parents often took us in "fieldtrips"; times in which they'd put us both in the car, drive hours on end to somewhere and then drive us back home. Most times it wasn't anywhere special, other times it was to my grandma's house in another part of the country or some other city far away.
Most often than not, it was through country roads since highways as we know them now weren't fully available yet. This, however, with an annoying 4/5 y-o who didn't grasp that asking "are we there yet" every 5 minutes didn't make us get there any faster was annoying.
As the oldest and easily annoyed, it fell on me to entertain my sister. So, I created what we today still know as "the flea theater". We use the diminutive term of flea in my mother tongue (pulguinha) for children as endearment when we mean to say they just won't stand still. This was an apt name since my sister wouldn't and it was my job to entertain us both.
My sister was always very pale and in those long car rides, my mom would often hung white fabric near the windows so to shield them. On top of that, my sis was used to carry around another white blanket she liked to sleep with. I often used those as curtain for our make-believe stage. The show had music, acting, jokes, story telling, you name it. I was a one man show until my sister started acting as well, singing and co-'writing'.
From then on, whenever our parents took us somewhere mildly boring, we'd pull out a "flea theater" to entertain us.