不適切だ
That joke is inappropriate.
その冗談は不適切です
That joke at a solemn occasion is inappropriate.
厳粛な、その冗談は不適切です
That joke at a solemn memorial service is inappropriate.
厳粛な追悼式で、その冗談は不適切です
That joke at a solemn memorial service in front of the family is inappropriate.
厳粛な追悼式で、遺族の前で、その冗談は不適切です
That joke at a solemn memorial service in front of the family while they mourn the deceased is inappropriate.
厳粛な追悼式で、遺族の前で故人をしのんでいる最中に、その冗談は不適切です