I had this idea of a running sketch where you see the first part and then the rest is spaced out between other sketches to signify time passing by.
INT. - TOILET - DAY
A man suffering from constipation sits on the toilet trying to go but without much success.
MAN
(straining)
Arrgh!
He then gives up frustrated and cuts to another sketch.
Returning again
MAN
(more straining)
Oh come on!
Cut to another sketch
Return various times to see him
reading the full set of Britannia encyclopaedias
building a castle out of matchsticks
doing a massive jigsaw puzzle
having made origami figures of Noah's ark and all the animals
Fed up now, he's red faced with sweat pouring out of him but still no joy. Then with a facial close up, blood trickles from his nose just as he tries one more last massive effort.
MAN
Yerughhhhhhh
Until finally he goes into a shocked look, falls off the toilet onto the floor, with a down the loo close up camera shot showing his heart beating away in the pan.