A blonde calls up her boyfriend and asks him to come round and help her assemble the giant jigsaw puzzle she bought at the supermarket that morning.
"What's the jigsaw picture?" he asks.
"A big tiger," she tells him "But all the pieces look the same and it's really hard to get it started."
Boyfriend drives over to blondie's place, walks into the kitchen and views the 'jigsaw' spread out on the worktop.
He looks at her, shakes his head, then says "Let's put the Kelloggs Frosties back in the box then I'll drive you downtown and we'll buy a real jigsaw."