Affordable housing means: Housing for people whose income is a certain percentage below the median income for an area, as determined by the U.S. Department of Housing and Urban Development (HUD).. There is no real cause for parental concern; it is descriptive vocabulary rather than risky behaviour. If your teen uses it, context will usually make the intent clear. A short, curious question about where they heard it is usually all that is needed to know whether to follow up.