Grumbles

I'm tired of your everlasting grumbles.

He always grumbles like a bear.

Tom is full of grumbles.

There's no pleasing Tom, he always grumbles about everything even when we've done our best.

When he is drunk, he grumbles and fights. When he is sober, he lies on whatever comes to hand and says nothing.

He grumbles a lot, but deep down he's not a bad guy.

They're just grumbles. There's no need to take it seriously.