Using up grant money before a deadline
Things to do (to the extent allowed by the terms of the grant)


Buy work laptops or other equipment.
Visit someone, send a student to visit someone, or invite a guest.
Depending on how quick the "quickly" is, go to a conference or organize a small workshop, or a summer/winter school.
Hold a networking event with your research group, or together with another group of possible collaborators, possible or actual.
If you have suitable publications, buy golden open access for one of them.


Things not to do

Try to get the money to yourself (except NSF grants in USA and summer salary). Try to keep it for later. Try to use it on something out of scope of the grant, like personal benefits without scientific value.