When this artist made a fun animation, he probably didn't expect to spark a scientific mystery.
Even though the gif is silent, people say they can hear the skipping pylon 'thud' or 'boing' onto the ground.
Psychology researcher Dr Lisa DeBruine polled Twitter users on whether they could hear the gif. At the time of writing, a remarkable 70 per cent of people who took part in the poll said they could:
If you can hear the gif, thank the McGurk effect.
This phenomenon occurs when audio from one sound is paired with the visuals of another sound and we hear a different result entirely.
In other words, what we see can change what we hear.
For example, in this BBC Horizon clip audio of a man saying 'baa' paired with a video of him saying 'faa' - this leads us to hear 'faa' instead.
However, the animation of the skipping pylons takes this phenomenon a step further; there is no sound in the gif, but the visual stimulus is still enough for people to hear a corresponding sound.
This effect is also seen in a study where 22 per cent of participants 'heard' faint sounds when shown a flash of light.
Surprisingly, all of this suggests that more people can 'hear movement' than the estimated 5 per cent of the population with synesthesia; a condition where one sense (for example, sound) is perceived as one or more other senses (for example, sight).
Correlated neuronal activity - where the brain 'expects' or 'predicts' something and then fires off the corresponding sense - may also have a part to play here, according to Andrew Kemendo the founder of app Pair 3D.
The gif's camera shake might also contribute to the phenomenon.
The gif's artist, Happy Toast, tweeted: