It's not what you think
The mother had washed her hair and just put rollers in - but she didn't have a hair net for them, so instead she used a pair of panties to keep them in place. Her 4 year old son had watched the process and was fascinated. His mother told him "Good thing there's only us here, so that nobody sees me like this." suddenly, the door bell rang. The little boy ran to open it, and outside stood a sales man who wanted to speak with the woman of the house. The son yelled "Mom, mom! Take off your panties! There's a man here who wants to talk to you!"