Artist Ben Rubin uses his iPad to add blue monsters to pictures taken of passengers on the Brooklyn subway. He then posts his creations to his Instagram and Facebook accounts under the name Subway Doodle.
The doodles are mostly cheeky and positive and he says so far he’s never had any complaints. In one case, he did a doodle of monster coming out of a cop car and a woman contacted him saying:
‘That’s my husband’s cop car! Can you send a hi-res image?’”
Here’s a small collection of some of his most famous doodles so far: