To shake or jolt something, especially a liquid or a medicine, in order to mix it or make it more effective.
When you succuss something, you are making it better or preparing it for use.
Examples:
She succusses the bottle of medicine before giving it to the child.
The chef succusses the salad dressing to mix the ingredients.
He succusses the ketchup bottle to get the last bit out.
The baby succusses the rattle and laughs.
I succuss the juice so it tastes better.
The doctor succusses the medicine to make it work faster.