What does the drink that Mio ordered look like in Episode 18 of Nichijou?
It looks like this:


  


Yes, you can order the exact customized drink that Mio ordered at Starbucks, given if the additives are available. The receipt says (the price is in Yen):

- 1 Grande White Mocca Frappuccino   510
- Shot                                50
- Hazelnut Syrop                      50
- Caramel Sauce                        0
- Chocolate Chips                     50
- Extra Whip                    (custom)
- Total                              660


Source: http://blog.livedoor.jp/laisser/archives/52073325.html