I do believe Spike is a valid name for a drink laced with drugs. And don't tell me Spike isn't a real name because if you do, the late Spike Milligan (sp?) will be turning in his grave.
I have never heard anyone say Earl when they mean Hurl. Also, Benjamin for $100. I have never heard. Sawbuck for $10 or Fin for $5, but Ben for $100? If someone asked me for a Ben I'd probably hand him a ballpoint.
Herb is one that works in Europe but not in America, due to differing pronunciations. In America, the H in Herb is pronounced in the name, but is silent when referring to a plant. Still, it make sense as an acceptable type-in since it works in British English.
I think a Cockney saying 'url for hurl is obviously short pronunciation for what they know is hurl. Other than that, anyone who thinks it's Earl is just confused about the word they're hearing.
Link for those who are curious
Shamus for detective is accurate as well.