Cold fingers - put them around your **neck**.

* The neck exhibits excellent blood flow and thus, heating power  
* The neck is easily accessible area of the body, unlike armpits, thighs, stomach (with all the layers of clothing)  
* At least for me, it is not very stressful  to press very cold fingers against the neck, compared to against e.g. stomach.

As for cold toes - I would probably try running, if excess energy is available.