noun
person who likes both alcohol and sweets
Describes someone who enjoys drinking and eating sweets in equal measure; a somewhat old-fashioned or literary term.
彼は盗人上戸で、酒も甘いものも大好きだ。
He is a 盗人上戸, loving both alcohol and sweets.
noun
person who can drink a lot without getting drunk
Refers to a heavy drinker who remains sober despite consuming large amounts of alcohol; also a somewhat old-fashioned or literary term.
あの人は盗人上戸で、いくら飲んでも顔色一つ変わらない。
That person is a 盗人上戸; no matter how much they drink, their complexion doesn't change at all.
The exact derivation is uncertain. The kanji 盗人 (thief) and 上戸 (heavy drinker) combine to form a yojijukugo with the given meanings.