The most sexual act you can think of

The act of doing coke - to 'funnel' it up your nose

When someone takes food from your plate without asking.

A device connected to a hose that is used to carry ones urine from the inside, to the outside of my dad's garage.

To give oral sex to a man by attaching a tube to his penis, while on the other end of the tube, a funnel is attached. Person giving oral must then, with much force, suck from funnel.

Common for System Administrators to use the word funnel as a Firewall/Tunnel

To gradually contort other's beliefs and gently lead them into your line of logic.