upside down: with the upper side turned toward the lower side Examples of UPSIDE DOWN Nobody noticed that the abstract painting was hung on the wall upside down. After the second hit, the truck rolled over into a ditch and landed upside down.

to look out: to be careful or cautious (also: to watch out) Examples of LOOK OUT We had a big drop in numbers and we have to look out for the safety of our kids. We were told to look out for a red van.

to drop (someone) a line: to write a note to someone Examples of TO DROP A LINE Please feel free to drop me a line with any of your thoughts regarding the page. I’ll try to get it up tomorrow, and will drop you a line when it’s available.  

by heart: by memorizing Examples of BY HEART Even though it was very long, Patrick recited his speech by heart, without looking at his notes once. I don’t know the directions to your house by heart; I’ll need you to remind me.

to be bound to: to be certain to, to be sure to Examples of TO BE BOUND TO “You’re bound to love this hit musical!” read the ad. Let me write down the shopping list; I’m bound to forget something.

as a matter of fact: really, actually (also: in fact) Examples of AS A MATTER OF FACT I know you thought I’d forgotten your birthday, but as a matter of fact, I’ve been planning a surprise party all along. As a matter of fact, I was hoping that New England would lose.