All the grandchildren wanted more and Grandpa ate three of them.
The grandfather "greedily washed himself," meaning he ate too much.
He ate three portions that were originally intended for his grandson.
This story could be humorous because it shows how the grandfather seized the opportunity and eagerly devoured a portion that wasn't his.
Possible Interpretation 2: A Play on the Word "Seconds"
Alternative Meaning:
If we understood the word "seconds" as a unit of time (for example, seconds as an interval), the sentence would take on a completely different, absurd, and humorous meaning. For example, it would mean that someone "ate" seconds of time, which is obviously impossible, creating a funny absurdity or joke.
Conclusions and additional comments:
För fullständiga tillagningssteg, gå till nästa sida eller klicka på Öppna-knappen (>), och glöm inte att DELA med dina Facebook-vänner.