What is a 'Yarakashi Senryu' (Blunder Haiku)?

This is the first project by Fu-san, who always praises my senryu.
Turn your blunders into senryu!

#YarakashiSenryu

Please let me participate.

Oh, I already have a feeling this will be so much fun.

Well then, I would like to compose three poems.
Starting with the first one.

Pressed the blue button, then turned pale

In this cold weather, I intended to buy a hot drink from a vending machine, but I accidentally pressed the blue button.

A cold canned coffee in my numb hands.
I couldn't help but turn as pale as the button itself.

Ah. I really messed up.

The second poem...

Postage fee
Insufficient funds, it returns to me

With postage prices changing every few years, how much is it exactly now?
I stuck on some stamps I had in stock and sent it off, but it came back to my mailbox with a notice saying the postage was insufficient.

Am I the only one who makes this kind of blunder?

Even the stamp sheets I won with New Year's postcards from a few years ago are unreliable these days.

Finally, the third poem.

Bulk buying
Eating it all as the deadline is nearing

This time, I tried to be conscious of rhyme.
I bought in bulk thinking it was cheap, but ended up regretting it when I had to rush to eat it all before the expiration date.
Doesn't that ever happen to you?

I would be happy if my blunders
could bring a smile to someone's face.

Thank you for reading.
Thank you for the happiness.
I am grateful for the connection we have made.