こんにちは！
「卒業旅行」は graduation trip と言います。
graduation は「卒業」という意味です。例えば graduation ceremony と言えば「卒業式」になります。
例：
I went to Paris for my graduation trip.
卒業旅行でパリに行きました。
ぜひ参考にしてください。
Only using 'graduation trip' in a sentence is perfectly acceptable.
Eg:
I am going on a tour of Europe for my graduation trip.
BUT, if you are traveling by car or bus, you could also use the term "road trip".
Eg:
I am going on a road trip through Europe to celebrate my graduation.
I hope this helps :)
文の中で“graduation trip”のみ使うことは全く差し支えありません。
例:”I am going on a tour of Europe for my graduation trip.”
私は卒業旅行でヨーロッパツアーに参加する予定です。
しかし車やバスで移動する場合は"road trip"という用語を使うこともできます。
例:”I am going on a road trip through Europe to celebrate my graduation.”
私は卒業祝いにヨーロッパを車で移動する長旅に出掛けます。
ご参考にしていただければ幸いです。
A 'Bash' is a party or social event. You would need to explain that it includes a journey.
For example it could be a 'pub crawl' where people go from one pub to another. It may be referred to as 'The graduation bash' if people already know what is involved.
Passing out = leaving a college or military academy.
A "Are you coming on the passing out trip. We're going by boat to have a meal on the island."
B "Of course. I wouldn't miss that!"
"post" means after. Post graduation trip means a trip after you have graduated.
It is common for students to take a year off from studying after graduating this is often referred to as a "Gap Year"
After graduation, we want to do something, so that we can remember the occasion.
"We are going to the US, to celebrate our graduation!"
"My parents are sending me to the UK, to honor my graduation."
"I want to do something to pay tribute to my graduation."
卒業後、私たちはそれを思い出すことができるように、何かをしたいといいたい場合は以下
例
"We are going to the US, to celebrate our graduation!"
"My parents are sending me to the UK, to honor my graduation."
"I want to do something to pay tribute to my graduation."
「私たちは卒業を祝うために米国に行きます！」
「私の卒業を祝して、両親は私をイギリスに旅行にいかせてくれた。」
「私は卒業式に敬意を示して何かをしたいと思います。」
1. A graduation trip is a trip that you go on after graduating.
2. Post-graduation trip.
The prefix "post" means after. So therefore, a post graduation trip is a trip that you take after
graduating.
A gap year it's a year between leaving school and starting university that is usually spent travelling or working. Usually, people in West countries call it "a gap year" but "a graduation trip" is fine to say.
"a gap year" は、高校を卒業してから大学に入るまでの期間をいいます。普通はこの間に旅行や仕事をします。
欧米では一般的に "a gap year" と呼ばれますが、"a graduation trip" とも言えます。
イギリス 
アメリカ合衆国 
南アフリカ 
カナダ 
