Here's what I found:
Derp:
German: of uncertain origin. Possibly a southern nickname for a clumsy person, from Middle High German talpe, tape ‘paw’. Alternatively it may be a northern topographic name for someone living by a ditch, Middle Low German delf (frequently an element in compound field names in swampy terrain). A third possibility is that it is from an old personal name, cognate with Anglo-Saxon deal ‘proud’, ‘famous’.
Bruh:
From German Brühan or Bruhan, the name of an old family of beer brewers, composed of early modern German breu ‘brew’ + the personal name (Jo)han (John), a common nickname for a helper.
Lol:
1 Dutch: variant of Bolle .
Amazingly, nobody in the United States last names their children their name Lol
