According to recent research, adults in Britain are buying toys for personal use in record numbers. Apparently adults wanting to relive their youth have purchased one in five children's building sets and action figures for themselves.
This phenomenon has seen the "kidult" market expand at three times the pace of the wider toy market.
A retail analyst described the trend as "possibly a reaction against the stresses of our fast-paced lives. Toys are fun and, when you are having fun, any stress you might be feeling goes away. "
The research also confirms the view espoused by many women: men never really grow up.
The vast majority of the purchases are made by males, according to the study.
American poet Dorothy Parker once said: "The only difference between men and boys is the cost and number of their toys."
If Parker were alive today, she might want to broaden her statement because a rising number of American men and women are buying toys.
American Demographics magazine reports 45 per cent of 20,000 adults surveyed nationwide said they had bought a toy or game for themselves or an adult friend in a typical year.
Popular toys for British adults include building sets, action figures, games and vehicles. Favourites are toys and characters from Star Wars and Lego "as they can evoke a feeling of nostalgia among the more mature fan base."
In the US, toy cars, Barbie dolls, stuffed animals and electronic video games are firm favourites.
One psychologist pointed to the ageing baby boomers "trying to deny they are getting older and looking for props such as toys to continue their youthful vigour".
Another said adult interest in toys is an age-old phenomenon and certainly not limited to baby boomers. He noted men have always been interested in engineering and construction as a pastime.
Generations ago, he said, men used lathes and other tools to produce working steam engines from scratch. Some would use kits like Meccano to build an infinite range of products then dismantle them to build something totally different.
"What has changed is that toys of old required the development of manual skills, the accumulation of technical knowledge, patience and dedication. These activities involved less plastic and more face-to-face collaboration with others than we see with today's adult toy hobbies."
Of course there are actual toys and then there are purchases made just for fun, so they are ostensibly toys. Think sports equipment, electronic gizmos and rarely-used kitchen utensils and power tools.
A Wall Street Journal columnist offered some guidelines for "when it's okay for an adult to buy what amounts to a toy":
• Don't turn necessities into toys. A car is a tool; buy anything nicer than a mid-range Honda and you're buying a toy.
• Toys that save money are more virtuous than ones that don't.
• If you have a toy that's good enough, don't be tempted by something better.
• Buy toys that won't lose value; 10 years from now I'll be able to sell my old South Bend 10K lathe for more than I paid.
• Buy toys that enrich others' lives too (like my Dad's Nikon camera that helped fill three decades of family photo albums).
While his guidelines don't say so explicitly, it's safe to say video games and water guns are toys, no matter if the owner is 9 or 49 years old.