A triple-hit of Black Fridays this year is a boon for Hell Pizza, which uses the day as a promotional opportunity, the firm's co-founder says.

Two Friday the 13ths have already taken place in 2012 - the first in January and the second last week. The third happens in July.

It is the first time there has been three Black Fridays in a single year since 1984.

Hell Pizza co-founder Stu McMullin said the firm had the busiest night in its 16-year history on Friday on the back of a $13 pizza deal and the firm's "pizza roulette" promotion.

The roulette involves a single pizza slice being drizzled with a super-hot chilli sauce, which the company claims is equivalent in strength to police-issue pepper spray.

The gamble for customers is they do not know which slice has the mouth-burning additional ingredient.

McMullin said Hell Pizza's sales on Friday were 39 per cent higher than normal and 52 per cent more deliveries took place than usual.

It was so busy, he said, that eight stores were forced to stop taking online and phone orders.

"We've never had to do that before."

He said the firm was not being affected by the heavy discounting being undertaken by other pizza operators, notably Domino's and Restaurant Brands-owned Pizza Hut. "A Hell customer is not price conscious," McMullin said, adding that $13 was the lowest the company went with pricing.

Meanwhile, he poured cold water on a media report that Hell Pizza was in the process of being sold to an Australian buyer. The company had been approached by three interested parties over the past couple of months but no offers were on the table.

Hell Pizza's founders - McMullin, Warren Powell and Callum Davies - sold the company to former Burger King owner Tasman Pacific Foods Group for around $15 million in 2006, then bought it back for an undisclosed sum in 2009.