commonly, when trying to buy ecstasy pills, a drug user will get "meth bombs" - rather than being pure MDMA, MDA, or related desirable amphetamines, meth bombs are laced with more dangerous drugs - often methamphetamines, as the name suggests. Taking a meth bomb will result in a lousy roll (or ecstasy "high"), a meth high, tweaking, or death.

Using a testing kit for ecstasy, a health-conscious roller will test pills before (s)he uses them, in the interest of avoiding ingesting meth bombs, speed, and poisons.

Literally everyone, ever. Including the writer of this definition.