Impress people with a free-hand drawing of a Penrose Triangle.
It looks difficult but is very easy.
I'll show you how to do it, just grab a pen and give it a try.

After drawing the triangle, you can round the corners to make it even cooler.

Step 1: You Need

Paper
Pencil

This is all you need for the original triangle.
If you want to draw one with rounded edges you'll also need:

Eraser
Not erasable pen

Step 2: Start

Draw a triange.
Try to make it as equiangular as possible.

Step 3: Parallel Lines

Draw 2 parallel lines to every edge

Step 4: Connect

Expand the edges of the inner triangle and connect them to the parallel middle lines

Step 5: Connect

Expand the lines of the middle triangle and connect them to the outer lines

Step 6: Finish

Draw short parallel lines at the corners and connect the triangles

Now your Penrose Triangle is finshed! Easy, right?

In the next step we'll round the corners to make it even more special.

Step 7: Round Corners

Add a little extra to your Penrose Triangle with rounded corners.
Just follow the instructions in the pictures.
Draw the corners round
Trace the lines with the not erasable pen
Erase the pencil lines
Finished!