Which is a sign that you should not drive?

Feeling excessively drowsy is a clear indication that you should not drive, as drowsiness significantly impairs your ability to operate a vehicle safely. When you are drowsy, your reaction times slow, your attention to the road diminishes, and your decision-making abilities can become compromised. Just like driving under the influence of alcohol, drowsy driving can lead to serious accidents due to decreased awareness and increased likelihood of falling asleep at the wheel. Hence, it's vital to recognize that even moderate levels of fatigue can be dangerous when driving.

The other options, such as having dinner with friends, being excited about a road trip, or wanting to go shopping, do not inherently indicate an inability to drive. These activities may not affect your driving capabilities. However, the risk associated with fatigue must be taken seriously, making it essential to ensure you are well-rested before getting behind the wheel.