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!
Should I go for it?
#giv'er#go hard#extreme#party hard#do it till you drop#go at it