overstatement -
I read all my text books today,my eyes are totally falling off!
Yesterday we had to run five miles in gym class,consequently,I don't think i can walk anymore for the rest of my life.
One of my friends can go under water for two hours and come back up perfectly fine.
understatement -
Even though I was the president of the class,I did not do much besides organizing all the events during the school year,and helping out fellow classmates.
I was kind of sick the other day; it really wasn't that bad besides that I broke my arm and my leg.
My room isn't very messy besides that there are about twenty books scattered around the room with ten or so pants or shirts hanging around my bed area.