two holes
Literal meaning: two holes or openings. Can refer to any object with two perforations.
This part requires two holes.
toilet with separate chambers for urine and feces
Refers to an old-style squat toilet or outhouse with two separate openings. Rare in modern contexts.
In the past, there were toilets with two separate holes.
riding double (on a bicycle, motorcycle, etc.)
Slang term for two people riding on a single bicycle or motorcycle. Usually written in katakana as ニケツ.
See also: ニケツ
Riding double is dangerous, so let's not do it.
Standard kanji spelling for the literal 'two holes' and the toilet sense.
Slang for riding double; usually written in katakana as ニケツ.
Compound of 二 (two) and 穴 (hole). The slang sense 'riding double' is a shortening of 二人乗り (two-person riding) with the character 穴 used phonetically or as a playful substitution.