Members of the Congress of the People have become obsessed with the shower taken by ANC president Jacob Zuma in 2006 after he had unprotected sex with "Khwezi", who later accused him of rape.
Zuma, who was acquitted of raping "Khwezi", was criticised for testifying to the court that he had taken a shower after the sex in a bid to protect himself from contracting HIV.
Now Cope has invented a song about it.
On Saturday in KwaZakhele, Port Elizabeth, thousands of Cope supporters sang "I left the ANC because of the shower", while holding one hand up over their heads, mimicking a shower with water trickling out of it.
Cope leaders have tried in vain to put a stop to the song . Last year, Cope was forced to apologise after its former youth spokesman, Anele Mda told a mass meeting in Mthatha that if Zuma became South Africa's president , "raping would no longer be a criminal offence".
On Friday in Port Elizabeth, Cope second deputy president Lynda Odendaal stopped Mda when she burst into the shower song on the party's open air bus trip around the city.
But when the manifesto was launched the next day, the song had become unstoppable.