Explanation:
In the given sentence, the appropriate punctuation mark to use is an apostrophe ('), which is used to indicate possession or to show that something belongs to someone.

Reason for using an apostrophe:
In the sentence, the word "Johns" is meant to indicate that something belongs to John. The apostrophe in "John's" shows that the sleep belongs to John. Without the apostrophe, "Johns" would be interpreted as the plural form of the name John, rather than indicating possession.

Function of the apostrophe:
The apostrophe is used to replace the missing letter "i" in the contraction of the word "John is" (John's). The apostrophe is placed between the "n" and the "s" to indicate the missing letter.

Corrected sentence:
With the appropriate punctuation, the correct sentence becomes: "John's going to sleep during the wedding was rather embarrassing."

Explanation of other punctuation marks:
In the given sentence, there are no other punctuation marks needed. However, here are some examples of other punctuation marks and their functions:

1. Period (.) - This is used to indicate the end of a declarative sentence or to show an abbreviation.
Example: "I am going to the store."

2. Question mark (?) - This is used to indicate a question.
Example: "Are you coming with us?"

3. Exclamation point (!) - This is used to indicate strong emotion or surprise.
Example: "What a beautiful sunset!"

4. Comma (,) - This is used to separate items in a list or to indicate a pause in a sentence.
Example: "I need to buy apples, oranges, and bananas."

5. Quotation marks ("") - These are used to indicate spoken or quoted words.
Example: She said, "I'll be there soon."

6. Colon (:) - This is used to introduce a list, explanation, or quotation.
Example: "There are three things I love: pizza, ice cream, and movies."

7. Semicolon (;) - This is used to separate two independent clauses or to separate items in a list when there are already commas within the items.
Example: "I went to the store; I bought milk, eggs, and bread."

By using the appropriate punctuation marks, we can effectively convey meaning and clarity in our writing.