Comedians joke about both political parties and audiences love it because it's satire and caricature. For example, watch George Carlin's stand-up comedy about Republicans by clicking on this link. To watch Dennis Miller joke about the Clintons click on this link.
With that said, both political parties change over time. For example, when studying the history of the civil rights movement, the first thing that one discovers is that President Lincoln was Republican and President Kennedy was Democrat. Income tax began when President Lincoln and congress created the Office of the Commissioner of the Internal Revenue Service ("IRS") in the Revenue Act of 1862 to fund the Civil War which killed one third of American men (Union and Confederate men combined), and by the end of the war ten percent of Union citizens had paid income tax. President Kennedy wanted to cut taxes.
Whether one is a new age Liberal Democrat or right-wing Republican depends on where one comes from; it runs in families and in neighborhoods. Overall, Americans are divided down the center. The 2000 presidential election was nearly a tie between former Vice President Al Gore (Democrat) and the future President George W. Bush (Republican), and it happened again in the 2012 election between President Barack Obama (Dem.) and former Governor Mitt Romney (Rep.).
The primary difference between Democrats and Republicans is where they go to get information about current events. For example, both of them listen to talk radio but they tune into different stations. For example, Republicans tend to listen to Coast to Coast and personalities such as Rush Limbaugh, Dr. Laura and Michael Savage, while Democrats listen to National Public Radio ("NPR") and KPFA. They both read the news on the internet but they go to different websites. Conservative Republicans prefer targeted niche sites versus Liberal Democrats' mainstream portals. For example, The Blaze, military news and up-to-the-minute financial sites are more likely to be read by Republicans, versus Yahoo and CNN which seem to be read by Democrats.