What's new on IELTS with Fiona

Today teachers in the UK went ON STRIKE.

I noticed the slogan of their campaign is simply "PAY UP".

What's the point of the "up" here?

Meaning of 'pay up': to give someone the money that you owe them, especially when they do not want to:

e.g. Eventually they paid up, but only after getting several reminders.

The 'up' particle on phrasal verbs often means to do something completely e.g.

• "Drink up!" (tell your friend to finish their drink so you can go to another bar)
• "Eat up!" (as above - finish your food)
• cut up, rip up, tear up = to completely destroy e.g. a piece of paper
• clean up, tidy up = to tidy/clean a room until it's completely tidy/clean
• add up – to add a group of numbers together until you reach a final sum. 
• heat up – to warm something until it is hot.
• grow up – to become an adult (until you finish growing)
• pack up – to pack until everything is in boxes.
• warm up – to sit in a warm space, such as by the fire or next to a radiator, until you are warm.

• use up – To use all of something so that there is none left