This couple's innocent holiday photo created a very NSFW optical illusion.

We have dirty, filthy minds. Sure, we probably knew this already. But this picture has proven it, once and for all.

To the pure of mind, it’s just a woman on a boat, in some lovely location, lovingly hanging her bare legs over her partner’s lap.

To the rest of us….

via GIPHY

The revealing optical illusion was posted to Reddit on Friday by user Summerie, with the caption, “My friend posted a new profile pic with her boyfriend, and everyone took a double take…”

Well, we did anyway.

And judging by the 68,000 upvotes on the post, so did plenty of other people.

If you need an explanation, then congratulations reader, you are both mature and pure of mind.

What those of us with our heads in the gutter are seeing is either:

a) a pantsless man sitting on his partner's lap proudly displaying his... erm, tackle;
b) a pantsless man sitting on his partner's lap proudly clutching said tackle.

Still don't see it? Try this - the effect is maximised in thumbnail form.

Oh, While we're on the topic of optical illusions featuring people on boats, please also enjoy this picture of a tiny man riding a female ferry passenger...

Did you do a double-take? Tells us in the comments below.