World championship yo-yo tricks.
Radio control helicopter aerobatics.
In the art of penmanship, the ultimate showcase of skill is called offhand flourishing. This combination of drawing and calligraphy was a natural outgrowth of decorations in pointed pen lettering. It was created at one shot without much in the way of preliminary drawing, which is where we get the figurative sense of the word “offhand.”

(Click to enlarge the picture above, which is from an 1880 penmanship manual called “Real Penwork Compendium of Penmanship.”)

It may not look like anything more than squiggly doodles to the uninitiated, but pictures made from flourishes are incredible difficult. It takes deep practice, good breathing, perfect posture, and a clear mind.
Here’s how master penman W.E. Dennis, in his 1914 book Studies in Pen Art, describes the challenge:
“It is doubtful if anything in penwork requires more real skill, sureness of stroke, delicacy of touch and absolute freedom of arm and hand than Off-hand Flourishing. Certainly none of the other work in this book offers the technical difficulties found in the flourished designs, the most difficult of all being the two swans facing each other. Lettering is more or less mechanical, but flourishing is quite the opposite. In this work the mind must conceive quickly the arrangement of harmonious, well-balanced curves, and the hand must reproduce them without hesitation. In addition to this, the penman should have in mind some harmonious design, pleasing in effect as a whole.”--------
Studies in Pen Art, by W.E. Dennis, available as a free PDF download.
Collection of free PDFs from IAMPETH (International Association of Master Penmen, Engrossers, and Teachers of Handwriting)