High school students in Surrey, B.C., were hoping to send a strong anti-pot message by wearing special T-shirts. But school officials shut them down after deciding the shirts may confuse younger students.

The shirts in question were simple enough: a white background with a large green marijuana leaf emblazoned on the front, and a red slash mark crossing through it.

Student Connor Fresenmaier said he and his friends are used to getting flack for their anti-pot views. "Insults, threats – they can get pretty harsh," he told CTV Vancouver.

But he wasn't expecting the shirts to get attention from school officials.

His brother, Duncan, said it wasn't long before the school's vice-principal called him into his office.

"The second I walked through the door, he was right in my face and said 'You need to either turn that shirt inside out or not wear it at all,'" Duncan Fresenmaier said.

The brothers' mother, Kelly, was eventually called in to try and convince her sons the shirt was inappropriate. But she said she doesn't understand the school's logic.

"How is it being misinterpreted?" she asked. "This is an anti-marijuana thing. They're definitely not promoting it."

Doug Strachan, of the Surrey School District, said the shirts are problematic because they show an image of a marijuana leaf.

"There's an illegal substance depicted on it in a large picture," he said. "That's what caught the staff member's attention."

Strachan added the image may also confuse younger students because the slash does not cross entirely through the front of the leaf.

The students were ultimately allowed to wear the shirts for the rest of the day, and attend classes as usual.

But several other students told CTV Vancouver that the message is clearly anti-marijuana.

"I mean, there's a giant red mark across it," said one male student, puzzled.

With a report from CTV Vancouver's Michele Brunoro