Sydney-based artist Michael Pederson creates small signs with humorous messages and tucks them all around his home city at places where you least expect to find them.

“Please wait here. Your future self will meet you shortly.” says one sign firmly implanted at the edge of a field. Or you walk into a public phone booth and find an official-looking sign announcing that it’s a time travel pay phone. “Never press 9” it warns, and you wonder if it’s real. Exit signs point at unnatural directions.

“I guess when you're doing anything in public, humour is a quick way to engage people,” Pederson told The Huffington Post. “I hope it brings up ideas as well -- gets people thinking about their headspace.”