Flame Retardant

• House Fire
• Fire
• Retardation
• Call
• House
• Wordplay

The joke plays on the double meaning of "retardant". It's meant to sound like "flame retardant," a substance used to slow down fires, while also using the term "retard," which is a derogatory and offensive term for a person with intellectual disabilities. It's a pun based on word association and uses a very insensitive term.