(n.) a friend you spend your free time with
Your lakelads and lakelasses are the friends you like to spend your free time with.
As much as it might be tempting to think these words derive from leisurely spending time together around a picturesque lake, the explanation behind this is a lot more straightforward than that.
As a verb, lake can be used to mean ‘to play’, ‘to act frivolously’, or ‘to take time away from work’. A laking-day, for instance, is a day off, or a day spent doing whatever you want, with no pressures at all. Laking-money is a child’s pocket money, meant to be spent on whatever they want. A lakesome person has a playful, frolicsome character. And lambs are said to lake at joggernoles when they playfully but heads in emulation of adult rams.
A lakelad or lakelass, ultimately, is a friend you like to spend this time with—whether at a lake, or not.