tarpit

Short definition from Wiktionary

Noun

1. 1
   A lake of asphalt formed when subterranean bitumen leaks to the ground surface. Such pits are important in forming fossil fuel reserves; they are also apt to trap passing animals, which become fossilized in the tar.
2. 2
   A service that purposely delays incoming connections in order to reduce the effectiveness of spamming and similar techniques.

Verb

1. 1
   To delay by means of a tarpit service.