I'm on call nights and weekends. I've been called 3 times since July and took the wifes car each time. Sorry. The calls were between 11pm and 2 am all 3 times. I have to get up and ride to work again at 5:30am. My daily bike commute of 25 min and occasional daytime car commute of 15 min with traffic is less than 5 min at night by car. All green lights and no cars at 30-50 mph. I feel like I should be riding my bike but then I would just take a sleeping bag with me and stay in the lab till morning. I shower there anyways.
I did get asked to do some overtime one weekend (1.5 time, yeah!!!) and arrived feeling awake and very chipper at 8am on a Sat and stayed in shorts and t-shirt all day. My co-workers were all grumpy and sucking coffee and talking about what a waste of a weekend this was. I even adjusted my brakes and some other things during some down time.

They griped about me being in a t-shirt and shorts with flip-flops while they were in leather shoes, khakis and nice shirts but then one of them noted that no supervisory elements were there and no clients would be either. This was just lab maintenance stuff. They felt silly then.