Odd Behavior

Every bearded dragon owner has moments when they look at their dragon and say "What the heck are you doing?"
Here is a break down of some of those odd behaviors.
Eyelid Bulging
Eyelid bulging or "popping" may take new dragon owners by surprise and even worry them. But it is a perfectly normal thing for a dragon to do. The reason for this odd looking behavior is to loosen skin on their face pre or post shedding. It also relieves irritation and itching. Often in adults you will see what looks like pink skin on the eye, again don't be alarmed this is the dragon puffing air into their second eyelid to relieve irritation.
Fun Fact- Bearded Dragons have an extra eye-lid, when the adults puff there eyes and they look pink it is the 2nd eye-lid membrane covering the eye.
The "Sexy" Leg
This action is known by a funny nickname to experienced dragon owners the "Sexy Leg". Dragons love to stretch out and relax just like any other animal. They spend a great deal of time sitting and laying down so this action helps stimulate blood flow and they really enjoy it.
Fun Fact- Baby dragons start doing the "sexy leg" from the day they hatch.
Waving
Waving is an adorable action to watch, especially in a baby dragon. What seems like a cute greeting to us is actually a serious defense for a baby or submitting adult. The dragons use this wave, or "arm circle" motion to show submission to other dragons. Baby dragons use this frequently when a larger dragon is in sight or to signal to each other that they are not threatening. Also females use this often during mating season to show a male she is submitting to him, click to read more on bearded dragon Mating.

Fun Fact- While Bearded Dragon "waiving" is cute it is important to remember that when a dragon displays this behavior it is feeling intimidated.
Dark Markings
Turning darker in color is normal for dragons. The dark marks on their backs and underbelly are most often due to cool temperatures, their color will even dull out or turn grey. Being darker in color allows them to absorb more heat. The dark marks are nicknamed "stress marks" which is only one of the reasons they appear. Be aware that if your dragon has a prolonged black chin, especially in baby/juvenile dragons, you should contact a reptile vet as this is can be a sign they are in pain, but this darkened body coloration is perfectly normal.
These babies are almost the same exact color, but the grey ones are showing darker colors due to being cold and trying to absorb more heat.
Spots on the belly of a juvenile dragon indicating stress or being cold. On some dragons these marks fade through the day, others have them constantly.
Fun Fact- Most Bearded Dragons in Australia look dark grey/black but most of them are just darkened in color on purpose due to their environment and it is very rare to find a dragon that is truly black/grey in the breeding community.
Black Beard
When a male dragon is entering sexual maturity you will see them darken their chin often. Now don't confuse this with the darkening caused by stress or cold this is entirely different. Males use this to show off to females and to ward off competing males. Dragons will also run and bob their heads feverishly to show they are the dominant one in the area. This most often happens in males but every once and a while a female may head bob as well. During mating season males act more territorial than ever. You might see dragons run at their cage doors with a black chin and bobbing their head aggressively at an inanimate object in the room that is not usually there.
An example of a Bearded Dragon "puffing" its beard which dragons do a lot in the mornings and it is not always a territorial display.
Examples of male Bearded Dragons displaying territorial behavior.
Fun Fact- Both male and female dragons "puff" their beards and can turn them black/dark grey
Open Mouth
When bearded dragons are at rest under their basking light you will see them with their mouths open. The reasons dragons rest this way is to regulate their body temperature. Much like an Alligator in the wild a dragon uses this open mouth to allow heat to escape and to avoid over heating. This is not to be confused with the behavior of a dragon opening its mouth at you when you go into its enclosure. Here you can read more on Handling.
An example of a hatchling baby opening its mouth out of fear and defense.
Examples of Juvenile dragons opening their mouths to regulate body temperature while basking.
Fun Fact- Bearded Dragons do not have teeth in the classic sense, they actually just have a serrated jaw.
Dragon Piles
When they are hatchlings they get along ok, but as they grow they fight for food and basking space. This happens even if they are well fed and kept in a larger cage. People often see what looks like cuddling under in a cage full of baby dragons and think "oh how cute they are friends". When really dragons 'pile' onto one another trying to get on top to steal the most heat and uv. Dragons really prefer to live alone and have all of the best spots and food for themselves. Their may look cute but it is the beginning of the dragons asserting themselves as the 'dominant' lizard in the habitat.