Why is 'boobs' or 'wriggly' more likely to get a laugh than, say, 'taxes'? What makes some words funnier than others?
Although you might not have thought about it much before, deducing the humour factor in words is a surprisingly complex process.
"Nobody has really done a good job at predicting humour in advance," University of Alberta psychologist Chris Westbury explains to The Canadian Press.
In a new study, Westbury looked at what it was about certain words that made them funnier than others – was it the meaning, the way they sounded, or something different altogether?
"Humour is, of course, still personal," says Westbury.
"Here, we get at the elements of humour that aren't personal; things that are universally funny."
The researchers used a data set consisting of 4,974 words, along with how humorous people found them, rated on a scale of 1 to 5.
With these ratings, and the words themselves, they then tried to pull apart what makes each word funny.
What they found is that there are two predictors to how funny a word is – form predictors (how the word is spelt and sounds), and semantic predictors (how the word is related to our emotions, and the meaning behind it).
The team found most of the words fell into one of six categories of funny words – sex, bodily functions, party terms, insults, swear words, and animals.
"We started out by identifying these six categories," says Westbury.
"It turns out that the best predictor of funniness is not distance from one of those six categories, but rather average distance from all six categories. This makes sense, because lots of words that people find funny fall into more than one category, like sex and bodily functions - like boobs."
The team used that information to develop a computer model, to see if it could work out which words humans found funny.
They then cross-checked the results with 74 participants making "humour judgments" on various words, to validate the model's performance on a list of over 45,000 words.
"I was amazed at how well we were able to predict judgments," says Westbury.
What was more interesting is they found that neither age nor gender seemed to affect what words we find funny, but culture and background does seem to play a role.
"I have an Iranian grad student who didn't really find the words we found funny to be funny," Westbury explains.
So what are the top 10 funniest words in the English language?
Well, according to the team, these ten words below are the most likely terms to make you giggle:
The research has been published in the Journal of Experimental Psychology: General.