What was your first newbie moment?

When I first drove my parents Class C, it felt like it was 40 ft long. I totally did not trust myself to change lanes without my sister in a car behind us using a walkie-talkie to tell me it was safe to get over. Now that I look back on it, I have to laugh at myself. Why? Well, the camper is all of 20 ft., bumper to bumper! I've since had a pickup longer than that thing. A couple years later, I completely forgot to put the house battery back in it after putting it on the trickle charger. 350 miles and 7 hours of driving later, no lights were to be had. Oops.