Change "Block" to "Drop Into Black Hole" in a Twitter account's dropdown action menu.

BlockHole-tweetdeck.css

/* Install the Stylish extension for your browser, add this code
as a new Style, and apply it to the domain 'tweetdeck.twitter.com' */

/* You can get Stylish here: */
/* Safari - http://sobolev.us/stylish/ */
/* Chrome - https://chrome.google.com/webstore/detail/stylish/fjnbnpbmkenffdnngjfgmeleoegfcffe */

/* Tweet improvements, comments, or corrections to @mcnees. */

/* ------------------------------------------------------------- */
/* Ever feel like 'blocking' isn't enough? Why not drop that     */
/* troll into a black hole?                                      */
/* ------------------------------------------------------------- */

/* Hide the 'Block' text in the user drop-down menu. */
a[data-action="block"] {
    visibility: hidden;
}
/* Replace the text with 'Drop Into Black Hole'. */

a[data-action="block"]:before {
    content: 'Drop Into Black Hole';
    visibility: visible;
}

BlockHole.css

/* Install the Stylish extension for your browser, add this code
as a new Style, and apply it to the domain 'twitter.com' */

/* You can get Stylish here: */
/* Safari - http://sobolev.us/stylish/ */
/* Chrome - https://chrome.google.com/webstore/detail/stylish/fjnbnpbmkenffdnngjfgmeleoegfcffe */

/* Tweet improvements, comments, or corrections to @mcnees. */

/* ------------------------------------------------------------- */
/* Ever feel like 'blocking' isn't enough? Why not drop that     */
/* troll into a black hole?                                      */
/* ------------------------------------------------------------- */

/* Hide the 'Block' text in the user drop-down menu. */
.block-text button {
  visibility: hidden;
}

/* Replace the text with 'Drop Into Black Hole'. */
.block-text  button:before {
  content:'Drop Into Black Hole';
  visibility: visible;
}

/* Make sure the background color changes when hovered over. */
.block-text:hover  {
  background-color:#0084B4;
}