I have a jumper that says "Make Don't Hate". What does it mean?
"Make Don't" is in the first line.
"Hate." in the second one.
At face value that phrase really doesn't make any sense, unfortunately. I tried to find reference to it online to see if it was a popular slogan or slang phrase, but didn't find anything.
The phrase Don't Hate is described in the Urban Dictionary. But it's not clear what adding the word 'Make' as a preface to it would do to its meaning.
I wonder where the jumper was made. Sometimes English slogans are printed on clothes and accessories made in other countries by people who don't speak English well. They might have heard an English phrase they liked and gotten it wrong. If this were the case there might be a word missing on your jumper, like 'peace'
Make Peace, Don't Hate
Or they could have just gotten the word order wrong. Maybe it was supposed to say
Don't Make Hate
which is a sentence that makes a lot of sense.
It could also be a bad translation of a phrase in another language.
Just to let you know, if you're talking to an American they probably wont' know what you mean when you say 'jumper'. In the U.S. it's called a 'sweatshirt'. The word 'jumper' is used in the U.K. and Australia.