Ninja technique of making hamburger (Ninja technique of making burgers) (忍法ハンバーガーを召し上がれの巻) is episode 664 of the 1981 Ninja Hattori-kun anime.
Hattori is busy running the hamburger shop with Shinzo, Shishimaru and Kenichi. All goes well... until Kemumaki interferes.
At the hamburger shop, the chef asks Kenichi if he can run the business for tomorrow while he's away. Kenichi agrees - but as soon as he gets home, he hands the reins over to Hattori, who grudgingly agrees.
The next day, Kanzo and the gang have arrived at the shop with Yumeko. He makes a success of it, but then a snooty man (who is really Kemumaki) turns up and impatiently asks for a hamburger. Hattori makes it extremely quickly, much to Kemumaki's annoyance.
A few successful makings later, Kemumaki returns, this time, disguised as an elderly woman. Hattori makes it. He then makes many more hamburgers in a big hurry.
As Kemumaki tries to leave, Hattori gives his muscles a slow-down massage and employs him as a clown. Just then, a scream rings out: Yumeko doesn't have mincemeat in her hamburger - but instead, she has one of Hattori's sandals! Hattori realises that this big blunder was all because of haste.