Makeshift way to drain a battery?
The "lead" of a modern pencil is made of Graphite.  Graphite is a form of Carbon. Carbon is what they make some resistors out of.

Your typical HB pencil has a resistance of around 150Ω-200Ω (I just measured the one on my desk - 172Ω).

Strip the wood from both ends of the pencil and wire it to the terminals of the battery.

$$
I=\frac{V}{R} = \frac{3.8}{172} = 22mA
$$

A 2000mAh battery would be flat in about 4 days.

To discharge faster, break the pencil in half or wire multiple pencils in parallel.

Note that drawing too much current through a single short pencil may get so hot it sets the wood of the pencil on fire.