can i have orange juice and a bowl of banana oatmeal with the stomach flu before going out? is it something the stomach can keep down?

No. I wouldn't consume either of those with our without the flu.  As others have noted, that a huge amount a sugar.

Orange us acidic -- not good for upset stomachs

Oatmeal  and bananas are full of fiber -- along not good for upset stomachs.

If you have the flu, you shouldn't be going out.  Stay home. Sip broth or tea. Try eating a saltine cracker or piece of dry, white toast to see if you can keep food down. 

I have no idea, but if you're diabetic, you're going to have a hell of a sugar spike. Fruit juices are loaded with sugar, not healthy at all. Just as bad as sodas, energy drinks and other drinks containing sugar. Oatmeal spikes blood sugar too.

I have no idea but for myself, both would be a trigger for my GERD's. Would not be a fun night.

There are many foods that can help relieve an upset stomach. Herbs and spices like ginger, chamomile, mint and licorice have natural stomach-soothing properties, while fruits like papaya and green bananas can improve digestion.

Juice and anything acidic should be avoided during the stomach flu.