Powered by the British public's unstoppable enthusiasm for toilet humour, the enticingly-titled How to Poo on a Date has carried off this year's Diagram prize for the oddest book title of the year.

With previous winners of the award including How to Shit in the Woods, American Bottom Archaeology and Cooking with Poo – which innocently drew its name from author Saiyuud Diwong's nickname, "Poo", Thai for crab – the prize is beginning to show a dangerous trend. "Diagram devotees have spoken, and spoken in no uncertain terms: poo wins prizes," said prize administrator Tom Tivnan, also highlighting the shortlisted title The Origin of Feces, which came in a narrow second to How to Poo on a Date in this year's public vote.

Almost 1,500 votes were cast for the 2014 award, with the pseudonymous Mats & Enzo's guide to dating toilet etiquette taking 30% of votes cast. Joint second place went to Are Trout South African and The Origin of Feces, with Working Class Cats coming in fourth.

Mats & Enzo are also the authors of How to Poo on Holiday, How to Poo at Work and How to Bonk at Work, which were nominated for the 2009, 2010 and 2011 Diagram awards, respectively. They clinched their triumph this year with a look at the important issue of portraying "at all times the image of a superhuman who never (or almost never) goes to the toilet".

"With three previous nominations, the two were in danger of becoming perpetual Diagram bridesmaids, like Beryl Bainbridge and the Booker prize or Peter O'Toole with the Oscars. It is a deserved, long-overdue victory," said Tivnan.

Editor of the book Roland Hall said he was "very happy and honoured that the British public thought our book worthy of first place in this much sought-after prize; we'd have been very disappointed to be number two".

"How to Poo on a Date is a humorous self-help title and it means a great deal to the authors and the rest of the team that put the book together that it should encounter such a splash of success," he added, humorously.

The Diagram prize, run by the Bookseller magazine, has been going since 1978, when Proceedings of the Second International Workshop on Nude Mice was spotted at the Frankfurt book fair.