Spinach

From Wikihack

Spinach is a type of food that appears in select tins. Eating it will provide 600 nutrition ^[1] (much more than other tins) and will increase your strength: "This makes you feel like Popeye!" (or "Swee'pea", if hallucinating)

The amount of strength increase is as follows:^[2]

Current strength	Gain
less than 18/00	+1 (75% chance) +1d6 (25% chance)
18/00–18/84	+1d10
18/85 or more	+1

Cursed tins of spinach contain a “decaying green substance”^[3] which makes you lose the amount of strength you would otherwise have gained.

The use of Spinach and its effects in NetHack is a reference to comic strip character Popeye[1], who gains incredible strength after ingesting the vegetable.

[edit] Source code references

1. ↑ eat.c, line 1121 spinach gives 600 nutrition
2. ↑ eat.c, line 1122; attrib.c, line 172
3. ↑ eat.c#line1100