When my daughter was a baby, she used to sometimes scratch her face in her sleep. One morning she had a bad scab on her nose. My wife washed it, kissed it and put some neosporin on it. Later that day when we picked up my daughter from daycare, the scab had magically healed (turned out it had just been a gross booger).
Now, years later, I still mess with my wife about it, call her booger kisser, etc... If she tries to give me the business about something, I can always say, at least I didn’t kiss a booger.