Fail in making a date

I am having my Japanese oral test tomorrow. While practicing with Pei Ying this afternoon, I made quite a big joke when I used the wrong words.

Situation : I need to ask Pei Ying out this weekend

I wanted to say: Do you wanna drink (nomimasu のみます) coffee in the coffee shop this weekend?

[Instead I used みます which means to look at]

And so my sentence became: Do you wanna look at (mimasu みます) coffee in the coffee shop this weekend?


and so the conversation continued...

Pei Ying: When are we meeting?
Siew Gee: How about ゆうびんきょく (post office) ?

[I actually had どようび(Saturday) in my mind but I don't know why ゆうびんきょく came out instead]

Pei Ying: ???????


Gosh...I sure hope that I don't make these silly mistakes tomorrow....I am gonna practice practice practice tonight!!!!