Smelly solution

Santiago loves making milkshakes
In my little milkshake maker: he shakes
And shakes that milk around until
All the cocoa is dissolved: it's yummy!
He shares it with his little brother Zac!
The only problem is that the shaker
Doesn't always make it back to the sink!
Sometimes it gets put down & left there
Where ever that is I don't know: though I ask!
"Where's the milkshake maker, guys?"
I get no replies: just silly eyes
Those "I don't know eyes!"
And of course the usual shrugs & denials!
I said to Santiago: "If we don't wash it; it will smell!"
His reply: "Let us leave it & find it by its smell!"
That's all very well for you to say my dear grandson but
I'm the one who has to wash it: smell it: splash it!
If it's too bad I'll guess I'll just have to trash it!