This is an alternative to the straw phonation exercise, for when you don’t have a straw handy.
Stand or sit upright, sensing for a dynamic, easy head-spine relationship.
Shape your lips around an imaginary straw, then bring your finger up to touch them, partially blocking the opening. Be mindful about bringing your finger to your head, rather than shortening through the spine to bring your head down to your hand.
Exhale an easy stream of breath and sound past your finger using an “Oh, wow!” inflection. Feel for continuous airflow and vibrations in the front of the face. This exercise might tickle your lips a bit. Aim for maximum ease.