Sharker

A "Sharker" is a term used by the Roblox Trading Community to call someone who lies about their item's value/other people's items to trick someone into accepting a bad offer as if it was good.
Sharkers usually do that to profit fast, and usually ruin all their reputation.
Very common with rare/semi-rare items, since they're not traded that much and not everyone know how to profit with them.

Roger: Can you accept my trade? My item gets 1 million overpays!
Pedro: Bro, stop SHARKING! You're lying, your item is bad! Sharker!

SK Era

SK Era (or Spawn Kill Era) is an era of the roblox platform that lasted from mid-2011 to 2019, and basically consists of a time when spawn kill was very common in games that allowed gear on the platform, mostly using gear to bypass the automatic force-field of platform games. This isn't as common nowadays, but it's still possible.

I will sk (Spawn Kill) Abner.

Sk era was annoying, thank god it finally ended.