The amalgamation of the word activity, and the British Army slang word "Jack" meaning selfish or lazy.
A jacktivity is something a multitude of people will do in order to evade hard work.
Person 1: "While we're in here, the smokers go outside every 5 minutes and evade the hard work."
Person 2: "That's such a jacktivity."
1. an assigned task that is nothing but a worthless, waste of time jack-off activity.
1. There was nothing worthwhile to do at work today so the boss assigned me a jacktivity to keep me busy.