This document presents a system for detecting sarcasm in tweets. It proposes a parsing-based lexical generation algorithm (PBLGA) to analyze tweets and classify them as sarcastic or non-sarcastic. The PBLGA uses part-of-speech tagging and parsing to extract sentiment phrases and situation phrases from tweets. It then compares the sentiment and situation phrases to detect contradictions that indicate sarcasm, such as a positive sentiment word with a negative situation. The system was implemented with an interface that allows users to input tweets and receives an output of whether each tweet is sarcastic or not. The algorithm achieved accurate sarcasm detection by analyzing the contradiction between the sentiment analysis and context of tweets.