This riddle asks: What gets easier to pick up the bigger it gets? It is a tricky one because the phrase “pick up” can have more than one meaning.
A clean modern answer is a radio signal. The stronger or “bigger” the signal becomes, the easier it is for a receiver to pick it up clearly.
There is also an older joke version of this riddle with a different punchline based on “pick up” meaning to flirt with someone. That version is dated and relies on a stereotype, so the signal answer makes the wordplay work without that baggage.
The key is realizing that “pick up” does not have to mean lifting something with your hands. Once you think of receiving a signal, the clue makes sense.
