Egghead
Tim's dad is a egghead that usually helps him with his homework.
Jeff is a egghead that studied engineering at MIT.
John studied chemistry so he stay on and be one of the eggheads at the University.
Meaning: a person who is highly academic or studious; an intellectual.
Etymology: An analogy of University professors with bald heads.
The whole nine yards
Bill went the whole 9 yards to prepare a perfect date with Tina.
Jack new he would need to go the whole 9 yards to prepare for his test.
John's boss is a tyrant that often forces him to go the whole 9 yards.
Meaning: "everything, the whole lot" or, when used as an adjective, "all the way,"
Etymology: The earliest known citation of the phrase in print is from 1907. The absense of the expression in print prior to that date argues strongly against any of the supposed mediaeval origins and clearly disprove the commonly circulated World War I and World War II origins.
Count your lucky stars
Thomas counted his lucky stars he was not expelled after fighting with his teacher.
Sarah counted her lucky stars after passing her driving test.
Ben counted his lucky stars when he was not fatality injured in a driving accident.
Meaning: be thankful for what you have
Etymology: We all have lucky stars assigned to us at birth by the Universe. Expression is taken from constellation and horoscope theory.