As an invitation for schoolboy humour they are hard to beat, but council officials can no longer see the funny side.

For years schools in South Africa's KwaZulu-Natal province have borne Zulu and Afrikaans names which, when translated into English, would brighten any CV. They include Mathangetshitshi (thighs of a virgin), Esinqeni (at the buttocks) and one that generations of pupils can empathise with: Tilongo (prison).

Now, in a much-needed overhaul of the province's education system, authorities say 15 unorthodox school names have to go.

"These are not educationally sound and will need to be addressed," Senzo Mchunu, an education executive councillor in KwaZulu-Natal, said at a recent launch event in Durban. "Such names are not inspiring."

The department was shocked to discover the number of schools that had "inappropriate and uninspiring" names, Mchunu added. "While we recognise that the naming of schools speaks to local characters, local achievements and eminent personages, in many instances, schools' naming was [not discussed with communities].

"The department is concerned about some of the names and it is for this reason that we will start consultation with all stakeholders about this."

Eyecatching school names in the province also include Mgwazeni (stab him), Ukufakwakhe (his death), Hlaba (slaughter), Nkawu (monkey), Mkhuthuzeni (pickpocket), Phuza (drink), Mbambankunzi (rob him) and Bhekumkhonto (look for spear).

Mchunu said schools bearing inappropriate Afrikaans names would also be changed. One candidate might be Vegkop (hill of the battle) high school.

Mchunu added: "We don't want to eradicate names of amakhosi (traditional leaders), which some schools are named after. But, as a department, we strongly feel there's a need for change. During the extensive consultative process we will allow a school to propose three names and one name will be chosen."

Villagers have criticised the name changes, saying they will destroy part of their heritage. South Africa's Sunday Times newspaper visited Mathangetshitshi high school in KwaMgilija village, about 190 miles (300km) north of Durban, and interviewed local residents.

"They related the tale of Chief Alpheus Bongizwe 'Mathangetshitshi' Nhleko, a well-built man who would parade his "taut thighs" – which they described as "easy on the eye" – while strolling through KwaMgilija," the paper reported.

"Nhleko died at the age of 62 in 1989 and donated a portion of his private farmland for the building of the school, which adopted the name he had grown fond of."

Muziwenhlanhla Buthelizi, deputy principal of Mathangetshitshi High School, denied that the name causes offence. "In fact, we're proud of it and its history," he told South Africa's Sunday Times. "We know the history of the name. It's unique and we do not feel there is anything inappropriate about it."

Prince Mbonisi Zulu, spokesman for the Zulu monarch King Goodwill Zwelithini, was quoted as saying: "We would not be happy if a part of Zulu history was erased without consulting the royal household."

The Sunday Times added: "Pupils interviewed this week giggled in embarrassment when asked for their thoughts – and almost all said they were not overly concerned about a change name."