Be dying for something/to do something
Definition 1 of 1
Pro Tip 1/3Intensity
The phrase expresses a strong desire, almost like a need, but is not a true emergency. 
After jogging in the sun, I'm dying for a glass of water.
Pro Tip 2/3Informal
This phrase is casual and best used in informal contexts, like conversations with friends. 
I’m dying to meet your new puppy.
Pro Tip 3/3Exaggeration
It's often an exaggeration, so use it to show enthusiasm rather than actual distress. 
I'm dying for the weekend to arrive!