Did someone just say that they use WD40 in their gun?
Brave man!
Maybe or maybe not, but it's worth a mention
WD40 has many uses beyond what you may expect of an oil, so it's worth having around
However one of its uses is not as a paintball lube
It would lubricate, but it would also eat orings, and not be too nice to some other parts
Pack tape (of various colours - it can also be used as an arm band or to colour your hopper), wd40 for some use, proper lube for your gun and batteries* (lots of them & ideally a battery checker)
* when something's not working start by changing the battery, and if it's still not working change it again. Never assume a fresh battery is good unless it works
Carry plenty of batteries and you won't need them. Don't and you will
Remember to have enough to cover gun & hopper, and the right types!