When Kira started going in season, she would pee on the bed. I was
able to convince my mom that she should be spayed after two heat
cycles (for other reasons though). During that time, I covered the bed
with a vinyl tablecloth to keep the pee from getting to my blankets.
And we had to work on some communication. She originally thought I
kicked her out of the room, but it was only off the bed.

She also had spearate anxiety for the first few years, so overnight
trips required the bed to be covered. She would vomit and/or have
diarhea on the bed (and only on the bed).

Now, Chase sends the true message, or at least he used to. Back when
he was a kitten, we had to work out some deals on the kitty litter
box. He is pickier than the other cats, so I had to keep it deeper and
clean it daily (I confess I was not scooping it that often before).
And he also has a preference for fine grain litter.

So, the first time I let it get too bad, he peed on the bed. When I
changed it to a pellet litter once, he peed on the bed. That was his
way of telling me he didn't like the letter (right back atcha). During
that time, he learned that I woudl respond quickly to a threat. So he
would go to the bed, meow to get me to look, and then dig like he was
about to use the bed. That was enough to send me to the litter box to
fix it.

Now, he doesn't have to go to the bed. He can just meow in that same
funny way, and I know what he wants. He is 4 now, and only peed on teh
bed 3 or 4 times during that first year. But it was enough to properly
train me, and he rarely has to remind me now.