Define "can't"

"Thus, you can't fuck someone in the ass with a dildo, according to the current edition of the Merriam-Webster Collegiate Dictionary, the Random House Unabridged Dictionary, the American Heritage Dictionary, and Webster's New World Dictionary."

\b/

The anonymous denizens of 4chan’s other boards — devoted to travel, fitness and several genres of pornography — refer to the /b/-dwellers as “/b/tards.”