Korean Family Titles
매형
maehyeong · Older sister's husband (for a man)
Relationship
me (her younger brother) → my older sister → her husband
Who uses it
A man, about his older sister's husband.
When you call them
Call him 매형 (also 자형 or 매부 in some regions).
When you talk about them
To others, 매형.
Example
매형, 누나랑 언제 놀러 와요?Maehyeong, when are you and my sister coming over?
Based on the standard etiquette of the National Institute of Korean Language; families and regions vary.