I have had these little boy and little girl stamps for a while and just haven't gotten around to using them. I was inspired by my son the other day when he came in and had muddy knees from playing outside! 
This is one of my favorite stamps! It is part of the Rambling Ted line from Penny Black. I have just recently found these Rambling Teds on one of my favorite stamp sites to shop and I was sad to learn that a lot of them are retired and you can't get them anymore. : O ( I will keep looking online mostly at ebay to see if I can score some of them!
Here are a couple more:
