What does it mean to say a man is a "lightweight"? [closed]

Question

Martin Shkreli, the 32-year-old “Pharma bro”, is a lightweight. What does this lightweight mean? Here is the original sentence:

Martin told me that he was a lightweight, something I’d never heard a man admit on a date (or ever).

Answer 1

According to Urban Dictionary, a lightweight is

one who can't handle their alcohol/weed.

Answer 2

This is one of those phrases that only makes sense with some background knowledge. Lightweight is used in horse-racing and boxing/wrestling to denote a weight class. Weight classes were established at some point in boxing/wrestling history to keep things fair and competitive. I'm not an expert on it so I'm not sure when or how the ranking system came to be. Lightweight is one of the smaller classes. (I'd be willing to bet that at one point it was the smallest class but without further research I can't be sure.)

At some point around 1809 according to http://www.etymonline.com/ it was used in the figurative sense meaning someone or something was small or not influential.

From dictionary.com

adjective

1. light in weight.

2. being lighter in weight, texture, etc., than another item or object of identical use, quality, or function: a lightweight topcoat; a lightweight alloy for ship construction.

3. without seriousness of purpose; trivial or trifling: lightweight reading.

4. of or relating to a lightweight: He's the new lightweight contender.

5. (of a horse, especially a hunter) able to carry up to 165 pounds (75 kg).

noun

6. a person of less than average weight.

7. Informal. a person who is of little influence, importance, or effect.

8. a boxer or other contestant intermediate in weight between a featherweight and a welterweight, especially a professional boxer weighing between 126 and 135 pounds (56.7–61 kg).

So, context. In this particular instance, the original quote is saying that he is a lightweight, which means he is not able to drink a lot of alcohol. Based on the rest of your sentence and that he was on a date. As another answer has also said, in American culture men like to be seen as being able to drink quite a bit without being effected. She was surprised he admitted it, or at least admitted it on a date.