lolsies is a swell abbrevation for the averageboring "LOL" response. If this swell abbrevation is used it means that it is even more funnier than just the average "LOL".
My mother just farted when she leaned over to pick up her purse at Costco, LOLsies!!!
a change of "lol".. when you say "lol" it sounds like "lul", then you have multiple of "lul", which is "luls", then you just add the "skies" which is pronounced "skeez"