A nickname for Embraer Regional Jets (ERJs), so called because Embraer is based in Brazil, home of the Amazon Rain Forest (Jungle). They are quite narrow and small, with only three seats across the entire cabin. Overhead bins are therefore very small, resulting in the inability of most carry-on luggage to be brought on board.

when you've done something so cringe you can't stop replaying it in your head and it stops you from getting on with your every day life

By analogy with Jumbo Jet, a large unwieldy plane with a dozen (or so) passengers per row, bathrooms and aisles that look like war zones, endless boarding, deplaning, food, and clean-up services, irritable flight attendants and elbow-fighting passengers.