Playing around or goofing off, especially when you should be serious or working.
Skylarking is usually seen as not very serious or responsible.
Examples:
The kids were skylarking instead of doing their homework.
Stop skylarking and pay attention!
She got in trouble for skylarking during the meeting.
The dog was skylarking in the park.
We were skylarking so much that we forgot the time.
The teacher caught us skylarking and we had to stay after school.