Answered January 17th, 2018

A season-high 38 points for Klay Thompson.
Klay is averaging career-highs in FG%, 3P%, FT%, eFG%, TS% this season.

When was the last time Klay Thompson scored 38 points in a game?

Interpreted as:

When was the last time Klay Thompson scored 38 points in a regular season game?