Drawing with a pen is usually challenging and takes longer time than expected but it is fun to work with. It helps you to improve your sense of concentration knowing fully well that you wouldn't erase it when mistake occurs.
Here, I used simple lines inform of squiggles to bring out shapes. The shape can be recognized as a panting dog resting on the ground.
The dog is called Lola, 
I first made ouline lines sketches...
...before adding those squiggles here.
You can see that the last step brought life to it.
Thank you.