A sentence that has legs and is escaping the page.
A sentence that contains two or more clauses but lacks proper punctuation to break it up.
A sentence that has too many punctuation marks.
A sentence that can only be fixed by adding a comma.
Dylan got arrested for being disordery - if only he calmed down this wouldn't have happened.
The turkey chased him all down the street, it was a sight to behold.
Bob burned the pizza again he forgot to take the cardboard out from underneath.
Unfortunately, there are no more single men in this town; you should try another.
When a comma is not used in a sentence to join two independent clauses.
When two or more commas are used in a sentence, breaking it up for no reason.
A love triangle between two sentences and a dastardly comma.
A sentence that has two independent clauses joined together by a comma.
Semicolon and conjunctive adverb.
Scrapping the sentence - there is nothing you can do to save it.
Putting a gerund in the sentence.
I went the library to study, but I got nothing done.
It is too late, we will never escape!
In my day, shoes were a luxury!
Marty, you're on fire again.
I've been to Mars, and I never want to go back!
I've been to Mars. I never want to go back!
I've been to Mars - therefore I never want to go back!
I've been to Mars, never want to go back!
Godzilla is attacking the city! Thank goodness Batman is on the case!
Godzilla is attacking the city, but thank goodness Batman is on the case!
Godzilla is attacking the city, however Batman is on the case! We need not worry!
Godzilla is attacking the city, so Baman will take the case!
All of the above.