Fill in the gaps with the correct option. Oh, ______ you go skiing tomorrow?

The sentence is a question about a future event, so the auxiliary verb 'will' is appropriate. The structure for a future question is 'Will + subject + base verb'. Therefore, 'Will you go skiing tomorrow?' is grammatically correct. The other options, 'do', 'is', and 'does', are used for present tense questions or with different subjects/verb forms.