The "That '70s Show" star was filming the 2004 comedy "In Good Company" with Quaid when his parents visited him on the set, and his castmate was rather taken by his mum, Pat.
"Dennis was very nice to them, you know, this huge star - they couldn't believe it," the actor told Kelly Clarkson on her U.S. talk show, "and as they were walking away, he said to me, 'Oh your mum's cute.' My mum overheard. it, and sadly my dad heard it too. My mum is a good looking woman... and she really took it to heart."
Some time later, Topher was waiting for his mum and dad in a hotel bar before the film's premiere, and he ran into Neeson.
"She [mother] was late [because] she was getting her hair done, because she was going to see Dennis again...," Grace recalled. "I saw Liam Neeson and he said, 'Why are you waiting here?' I told him this whole story and I said, 'Just get out of here, you don't want to meet my parents.' And he said, 'I'd love to meet your parents.' "
"So they came in and Liam Neeson - I've never seen him again but I think this is the funniest thing ever - he goes, 'Patricia, it's so lovely to meet you. Dennis Quaid told me you were cute, but he didn't do you justice.' And she, like, passed out. She couldn't believe what was going on."