to "gas (someone) up," imagine you are the gasoline that exacerbates your friend's spark in whatever moment, some good moment. some say it's like motivation but that's not the same--you "motivate" one who has no spark. but you "gas up" someone who already showed a little something and you want to bring out more. gassing someone up is generally expressed as extra loud praise, cheer, joy; it's a positive trend among friends that helps people who lack confidence be the best person they can be
"if your friends don't gas up like this for graduating, are they really your friends?"