durag or du-rag, also called a wave cap, is a cap typically worn to accelerate the development of waves, braids or dreadlocks in the hair.[1] Durags are also used to keep wave patterns from shifting while sleeping.durag or du-rag, also called a wave cap, is a cap typically worn to accelerate the development of waves, braids or dreadlocks in the hair.[1] Durags are also used to keep wave patterns from shifting while sleeping.durag or du-rag, also called a wave cap, is a cap typically worn to accelerate the development of waves, braids or dreadlocks in the hair.[1] Durags are also used to keep wave patterns from shifting while sleeping.durag or du-rag, also called a wave cap, is a cap typically worn to accelerate the development of waves, braids or dreadlocks in the hair.[1] Durags are also used to keep wave patterns from shifting while sleeping