Police were called to Pearson's Way in St Peter's, Broadstairs, Kent, after an incident involving a man reportedly wearing nothing but a pink thong.
He reportedly stood in the middle of the road before trying to strangle himself with a bra.
A witness claimed he then placed car keys in his anus.
He was described as shouting and being covered in blood.
Witnesses reported a "horrific" scene with people screaming.
Police say a 40-year-old man from Broadstairs was arrested on suspicion of assault on Tuesday and is in custody.