A straddle is any set of offsetting positions on personal property. One example, is a put and call option on the same number of shares of a particular security, with the same exercise price and expiration date.
Definition of flack for English Language Learners. : a person whose job is to make people like or be interested in someone or something.
Quack, in the sense of a medical impostor, is a shortening of the old Dutch quacksalver (spelled kwakzalver in the modern Dutch), which originally meant a person who cures with home remedies, and then came to mean one using false cures or knowledge.