noun
forgetting the old year's troubles
Refers to putting aside the hardships of the passing year, often in the context of year-end parties (忘年会).
忘年会で一年の苦労を忘れる。
At the year-end party, we forget the hardships of the past year.
noun
forgetting age differences
Describes a social atmosphere where people of different ages interact without regard to age hierarchy; often associated with 忘年会.
忘年の交わりを結ぶ。
They form a friendship that transcends age differences.