But this dad from Brazil dealt with this situation in one of the sweetest ways ever.
Thiago Sagrilo decided to paint his finger nails in support of his son, Arthur, who was teased because he enjoyed wearing nail varnish.
He posted the photo on Facebook and proudly had his nails on show when he picked four-year-old Arthur up from school.
"Our nails will remain painted. Actually, we need a retouch," Mr Sagrilo told HuffPost Brazil. "I try to keep my nails painted when he does. The colours change constantly.
"Arthur knows colours are for everyone and every day he tells us that he has a new colour. One day it’s blue, the next black, then pink."
Thiago and his wife, Laura, said their son was bullied and called a "little girl" because he enjoyed paintingd his nails and had long hair.
Previously Laura had shown classmates pictures of men with long hair to calm down the name-calling.
"We always try to act and handle the issues immediately," she said.
Having painted their nails to support their son, the couple have received hundreds of messages congratulating them for being so open with their son, with some people even asking for support.
"I still do not know how to handle the [messages of] congratulations, because we both see this as the minimum requirement to raise a child," Laura added.
Although Arthur isn't quite sure of what all the fuss about, his parents said he's pretty happy watching TV... with his nails painted.
But it seems that painting your nails is no longer just a fashion statement.
In April, another father painted his nails blue to raise awareness for Autism Awareness month. Brian Batey painted his nails blue, and urged others to do the same on his Facebook page.
"You are helping me change the world for autistic people and those who love them just a little at a time," he told HuffPost UK Lifestyle at the time when people began painting their nails in solidarity.
Batey was diagnosed as being “in the Asperger’s range” on the autism spectrum two years ago and his 18-year-old son, Nathan, has Asperger’s syndrome.
He was inspired to paint his nails after his friend did a similar trend and painted her little girl's nails blue in honour of the awareness month.
"It made me wonder how many more I could get to do it," he told us.
312 people took part and sent in their photos of blue-painted nails.
These dads seriously know how to support their children through the wonders of nail varnish. And we love it.