For father-son bonding, there's nothing like a little trespassing on heavy machinery.
(Click the image for a larger version.)
Acting on a tip from Mom-O, Finn and I scrambled around a big piece of equipment (an asphalt-devouring Wirtgen 1200 F cold milling machine, I'll have you know!) that was parked in our neighborhood. Finn (and Leo) got a big kick out of sitting in the driver's seat, playing with the steering wheel (but not the God-forbid-it-turn-on knows/switches), and plugging various lights into the tracks. Our boy now knows what a grease gun is.