Right now I'm working through Nihongo-Sou-Matome for JLPT N3. I recently came across an example sentence that I'm a little confused by. The sentence is:
試験が終わった!今日は飲んじゃおう!
I get that this means: The test is done! Let's drink today!
What I'm confused about is that I thought that しまうwas only used for expressing regret at doing something (for example, ケーキを全部食べちゃった - I ate all the cake (yikes)) or saying that you did something completely (for example, 宿題をやっちゃった - I did all of my homework).
So in this example, what does 飲んじゃおう mean? Does it suggest that the drinking will be regretted later?
試験が終わった!今日は飲んじゃおう!
I get that this means: The test is done! Let's drink today!
What I'm confused about is that I thought that しまうwas only used for expressing regret at doing something (for example, ケーキを全部食べちゃった - I ate all the cake (yikes)) or saying that you did something completely (for example, 宿題をやっちゃった - I did all of my homework).
So in this example, what does 飲んじゃおう mean? Does it suggest that the drinking will be regretted later?