"I'm a paediatric nurse and I'm from the deep, deep south, so I butcher everybody's name," Foster said.
"If it's not something super simple like Ben or Sally, I'm gonna butcher it.
"So, I see a kid's name on our computer and I say 'oh, Liam, I got this. L-I-A-M. Liam. Easy'."
But it wasn't that easy.
"I go out, call the kid's name, nobody moves. Call him again. Nobody moves. Call him again nobody moves," Foster said.
"Finally this mum stands up and says 'do you mean 'Yum?' And I say 'no, Liam?' and she said 'yeah, it's short for William'."
Foster performed a "mind-blown" gesture for the camera to sum up the moment she learned that "Liam" wasn't always 'Lee-Um'.
The video was viewed millions of time and thousands of commenters weighed in, with one saying: "As a mum of a Liam, I am perturbed."
Others shared their own experiences with unusual names.
"Had a patient named L-A, I called for LA. Mum quickly informed me it's pronounced Ladasha and did I not see the dash? Ummm okay," wrote another medical professional.
"Had a student named Justin, last name Case. He said 'My mum thinks she has a sense of humour'," someone else commented.