Rob, the boys and I were at Rob's grandmas house a few weeks ago on Friday night.  Noah spilled milk all over his clothes, so I changed him and put the wet clothes into the diaper bag.  We got home that night, put the kids to bed and watched tv for a while.
In the middle of the next week, I got into my car in the morning noticing that it smelled like a poopy diaper.  I scanned the car, but didn't see one.  I drove to school and eventually didn't notice the smell.  After class, I got into my car again, and there was the smell.  I checked under seats and still couldn't find anything.  I got home that night and told Rob about the smell, but left it at that. 
The next morning, I got into the car and it smelled even worse.  I saw the diaper bag on the floor, opened it and almost passed out.  It was those milky clothes.  Phew, I solved the case.  I put the clothes into the hamper and put an air freshener into the car.
Early this week, I noticed that the boy's room smelled like a poopy diaper.  I thought maybe Rob had changed Noah's diaper and it fell behind the changing table.  I got the boys ready for the day, took them to Amber's house and came home to find the dirty diaper.  I looked behind the dresser, under the crib, under Ryan's bed, in the toys, but couldn't find anything.  Oh, well.  I'll start the laundry.  I opened up the closet to get the hamper, and there was that smell, even stronger. 
Yup, it was those dang milky clothes, sitting at the bottom of the hamper that I had forgotten about.  It takes me a while sometimes...