i'd rather drive on the left side of the road

means that you would rather drive into oncoming traffic then to do something

ugly person : wanna kiss??
me : i'd rather drive on the left side of the road 🙄

I'd do that all day

When something is such a good deal or idea that you would gladly take it at any time

Them: $500 a month utilities and internet are included
You: I'd do that all day!

If I'd known you were coming, I'd have shaved my beard

Da "parody on da cake-baking saying" remark dat you smilingly say to a cute chick whom you've unexpectedly met somewhere, and you are savoringly pressing her soft warm palms against yer fuzzy cheeks.

I always love joking around about, "If I'd known you were coming, I'd have shaved my beard" wif pretty girls whom I befriend; said humorous remark always gets da biggest amused giggle-fits outta dem.