Years ago I enjoyed a bite to eat with Dharmesh Shah and my brother Andy and we talked about startup names. We’d just raised a small angel round with Dharmesh as the first investor in. Our idea was to create eBay for renting physical products (mostly bouncy castles), and we’d dubbed it Rentabilities. While Dharmesh was incredibly supportive, he urged us to think about changing our name.

A fun, banter-filled conversation began while feasting on one of Dharmesh’s favorite dishes, arancini. We agreed there were so many issues with the name Rentabilities: All the i’s, it was hard to spell, and it had five syllables. But our startup had so many other problems besides our name. We convinced Dharmesh we’d put our name problem on the back burner for a while because while it wasn’t a very simple name, the domain name was available and we passed the “Grandma Test.”

The Grandma Test was a thing we coined at this dinner. At the time, our grandmother was in her late 80s. She and my late grandfather were always curious about what Andy and I were up to. We told them about how we’re going to help thousands of people rent bouncy castles and call it Rentabilities. My grandmother’s brain is packed full of information and wisdom from over the years. Which means, even by her own admission, she sometimes forgets stuff. A week later Grandma Cook remembered the name of our enterprise and what it did. We passed the Grandma Test.

Years later we shut down Rentabilities joined HubSpot. As life powers on, I keep taking the Grandma Test.

Last winter, Andy and I launched a side project called NanaGram, a gift we gave to our late grandfather on his 94th birthday. We wanted to make our grandparents feel more connected. We gave our family a unique phone number, asked them to text message their photos to it, and every month we’d print and ship 4×6 photos to our grandparents. When I dropped off the first set of photos to my 94-year-old grandparents I left some business cards and magnetic fridge pins. I came back a week later to find the fridge totally covered in photos. The walls were covered in scotch-taped photos too. NanaGram passed the Grandma Test. I came back a month later and something unexpected happened.

My grandmother loved the idea for NanaGram so much that she started pitching it to strangers. Anytime anyone would enter her house, whether it be a plumber or a nurse, she’d ask them “do you have any kids?” then listen intently to stories about other people’s kids and grandkids. Then she’d ask, “do you take lots of photos of your kids?” and again patiently listen and talk all about her mutual love for photos. Finally, she’d say “well my grandson has a business called NanaGram…”, and tell them all about it. Then she’d grab a business card and hand it to them with a big smile saying, “Take a ticket!”

For further reading on startup names, check out Dharmesh’s SMART checklist. (The Grandma Test is all about nailing the M.)