"Regular or Decaf?" joke

A man walked into a restaurant and seated himself. Soon, the waitress came over to take his order.

".. . and to drink?" she asked.

The man said he would like coffee. The waitress promptly returned with a cup of coffee, but spilled it on the man's lap when she stopped at the table.

"Oh my God! I am so sorry!"

"That's OK," the man said, sopping up the puddle on his pants with his a napkin, "But tell me, is this regular or decaf?"

"Regular," she replied.

"Oh great, now this thing is going to be up all night!"