You see, I don't have a microwave (more on that craziness later, if you care to know). And sometimes, we go out and run errands in the morning, and then we're desperately hungry when we come home. If I'm sane enough to think of that on my way out, I take a minute to throw some leftovers in the crockpot on high for the couple of hours that we're gone. Then we can literally eat right away upon our return, which has saved us all some tears and meltdowns (mostly from me. Tears have reduced by 47.3% since starting this).
I've done it one of two ways, depending on the kind of leftovers I'm heating up. If it's something that's relatively dry ... quiche, or pizza, or pork chop and potatoes for example ... I wrap it up in foil and just put it in the bottom of the crockpot. Turn it on high, put the lid on, and come back in two hours to a delicious lunch perfectly heated. Bonus: cleanup is minimal. Yippee.
Another way to tackle the heating up is to find a heat-proof dish that fits in your crockpot (I have those freezer-to oven-to table pyrex dishes), fill it up with something a little soupier (pasta and sauce, for example) and put an inch or so of water in the bottom of the crock pot. Place the heat-proof dish in the water, put the lid on the crockpot, and turn it on high. And again, yippee skippee for little cleanup and a hot meal.
Perhaps you are thinking, "Why not just put the leftovers IN the crockpot and heat them up that way?" Well, on low they sometimes don't heat up enough, and on high they sometimes get crisped and weird. Cleaning up is more challenging. Trust me on this. But by doing it this way, they are nicely warmed through (even steamed, in the case of the pasta), and about as edible and delicious as they were the first time around. And you won't have to soak and scrub and soak again and scrape your crock pot! Win.
Strange? Definitely. Helpful? Hopefully!