Can be anything you want it to be. Such as......
Someone standing in dog shit and angrily looking down at his shit stained kicks "happy days ladπ"
Or a lad who has just bummed a stripper and is now spilling the beans to the lads down the boozer......
"happy days lad π"
Was bucking this slut up the shiter and when I pulled my bobbies nut out if her back eye I only had a bit of sweetcorn stuck in me japs eye......happy days lad (angry context)