thumb on the scale

brown thumb

A lack of skill at growing plants; a poor gardening skill.

butcher's thumb

A dishonest practice in which a butcher uses their thumb to add extra weight to a scale when weighing meat.

fash one's thumb

To bother oneself; to worry about something.

green thumb

A natural skill for gardening.

off the scale

Far in excess of what is normal or measurable.

returns to scale

a function describing how returns scale when production increases in the long run

rule of thumb

A general guideline, rather than a strict rule; an approximate measure or means of reckoning based on experience or common knowledge.

thumb a ride

To hitchhike.