verb
This definition (not the noun 'giver' which means 'one who gives') is a North American word meaning to 'go hard' at something. Usually refers to (but not limited to) drinking, fast driving, partying, working, and possibly sex. Mostly used by Canadians; probably a short form of 'give 'er shit' meaning give it some gas, or put some muscle behind it!
giver(verb): to give your all; to get completely hardcore on/about something; to party extremely hard; to indulge in numerous fun activitiessimultaneously.
Its your buddy's stag or something and you just shotgunned 2 in a row.
Best man: Alright lets go buddy time to giver, 1 more.
Guy about to be married: OK!!
*They shotgun*
Almost married dude yacks then says: I fuckin gaver and thats all that counts!