What does Japanese mean by digging a sack ??

This is a joke when Chinese people learn to talk to Japan. The conversation between two people is complete.
"Where are potatoes ?"
"Go to the potato suburb to dig ."
"Dig a sack ?"
"Dig a sack ."
Are you kidding me ~~~
My classmates used this method to tease the teacher in Japanese classes,
"Teacher, Senior One (he said in japanese), what does it mean ?"
The teacher never thought for a long time. He said, "that's what you mean !"
Dizzy enough ~~~~~~~
So if you want to learn Japanese, never be fooled by such sentences.

The first Japanese sentence: "Where can I dig potatoes? Dig a bag in the potato field ." Does it mean "have you eaten? I have eaten, and I am exhausted ." The second Japanese sentence: "You eat some food, you eat some food, I eat your sweet potato ." Does it mean "have you pulled it? Have you pulled it? What did you pull ?" It can be seen that Japanese people often eat things pulled by Chinese people: Haha, Hahahaha ....
"You eat melon, you eat melon, I eat your sweet potato ." Does it mean "have you pulled it? Have you pulled it? What did you pull ?"
I have added some notes: This is the pronunciation of Qingdao dialect. "Gala, Qingdao, dug a sack. Japanese is: Japanese.