system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How to whistle with your fingers?
gpt
Take your thumb and any finger (middle works best for me). Bring the tips close together, but leave about a 1/4 inch of space between them. Use your fingers fold your tongue back. Curl your lips around your fingers and blow. It takes a lot of practice. 

Edit:  Wow! Gold! This is awesome!! Thank you kind stranger!