Say Humbly
There’s a cross in your mouth, so the things you say are very pious. Everything you say, you say humbly.
Imagine yourself with a cross in your mouth, saying all kinds of humble things. "Oh no, I'm not that good." "Oh no, my mustache doesn't look that great."
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As you're saying all these humble things, you're also mowing (もう) your neighbor's lawn. Your neighbors love you so much, because you're so humble, and you mow their lawn for them.
Imagine mowing your neighbor's lawn while you say humbly how bad you are at mowing lawns. What a good neighbor you are.