他人をからかってはいけない。

another person; other people; others; unrelated person (i.e. not related by blood); outsider; stranger

indicates direct object of action; indicates subject of causative expression; indicates an area traversed; indicates time (period) over which action takes place; indicates point of departure or separation of action; indicates object of desire, like, hate, etc.

to ridicule; to tease; to mock; to chaff; to razz; to banter with; to make fun of; to poke fun at; to make cracks about

if ... then; when; and; why don't you...?; the more (one does something); because; since