When you summon a demon, you yell, "SHOW yourself!!!"
I will raise my sword and open my mouth to summon the troops: "Chaaaarggeee!!"
summon (never used by itself! But you need it to say the following jukugo:)
Very polite way to say, "let's eat" to a superior person. This sounds like you don't need it, but when you go to a restaurant, YOU, believe it or not, are a superior person, and so you'll need to know this word to understand what the waiter is saying to you.