off balance - unaware; off guard
　　on the go - working or doing something all the time
　　on pins and needles - nervous; anxious; full of anticipation
　　on purpose - deliberately; intentionally
　　on the blink - not working properly;broken
　　pick up the tab - pay the bill or the cost of something
　　piece of cake - easy
　　play by ear - act spontaneously; without planning
　　pill it off - accomplish
　　pull one’s leg - make fun of somenoe in a playgul way; make somenoe believe something that is not ture
　　quite a few - many