HAT 🎩

If you do something ‘at the drop of a hat’ then you do it very quickly, without hesitation.
‘He always helps me at the drop of a hat, he is such a good friend.’
'Hats off to someone' means congratulations.
‘Hats off to Susan and her team for building such a wonderful boat.’
To 'go hat in hand' to someone is to go to someone with humility, usually asking for something or some type of favour from them.
‘After the argument he came back, hat in hand, and asked me to help him with his project.’