If my new pjs are 100% cotton, why does the label say "do not tumble dry"?

[PuppyDrunky]

Other than just to piss me off etc?

Cotton'll be ok won't it?

erm because they're cotton.
cotton shrinks

my cotton pyjamas are fine in the tumble dryer.

Just in case they shrink and you ask for your money back.

But everything else I've got that's 100% cotton says it's ok in tumble dryer!!?

Because they may well shrink (unless they are pre-shrunk). May still be fine afterwards, if you've got plenty of room in them, though.

I might sneak them in on low... they're quite big anyway! Hope I don't put on too much weight at Xmas...