VBA Code current date plus two digit serial number

Question

i want to create a vba code that will upon double clicking a cell (A2:A9999) the current date and a two digit serial number (01 to 99) will auto-fill (20171031-01).

Example

Double click cell A2
-20171031-01

Double click cell A3
-20171031-02

Double click cell A4 (2 days later)
-20171102-01

I am new to this and i cannot seem to get it to work