All drivers honk in Ghana, all the time. There are many things a driver might be trying to express with their honks, and I've listed all the ones I've come across, in order of frequency:
1) "I'm an empty taxi and I really want a fare."
Taxis love to honk at you, especially if you are white, because the only reason you would be white and walking around instead of in a taxi is because you are not smart enough to know how to summon a taxi. I get this frequently while waiting for a tro-tro: a guy will come up and say "Where are you going??" and I'll say "Kaneshie" and he'll grab my arm and drag me to a taxi. No, sir. I don't want a taxi. That is why I'm waiting for a tro-tro. Then he'll say "Oh. You wait over there. Tro-tro will come." Yes, thank you, I know. That's why I was waiting there in the first place. Whew. Sorry, little rant there. Ghanaians love to help me, but they don't often realize that I don't really need help.
2) "I'm driving recklessly fast, so you'd probably better move"
If there is room to drive too fast, a car will drive too fast. This a rule with few exceptions.
3) "I'm going to drive where you are walking and want you to move immediately."
Cars have right of way in Ghana. Always. It is pretty difficult to cross streets because they rarely slow down at all. I've definitely had times where, had I tripped and fallen, I would have been run over. Kinda amazed I'm still alive.
4) "I'm too lazy to use my turn signal."
Ghanaian drivers tend to take the lines that distinguish lanes as suggestions. On a 3 lane road during rush hour (or rush hours, as it is here), you can usually count 4-6 vehicles next to each other. They all change lanes all the time too, in hopes of getting ahead of that one driver. they do this by waving out the window in a sort of shooing motion at the other cars and/or honking to alert them that they'd better move of they'll get hit.
5) "I can't believe you aren't driving yet, the light has been green for approximately 0.5 seconds!"
Traffic is pretty awful here, since there is one main road that everyone uses to get from Legon to Accra, and it is backed up between 7:30-10:30 AM and 4:00-7:30 PM. Not super surprising that people have road rage.
6) "Drive faster!"
This in lieu of overtaking them, though usually they just overtake them (safely, or not)
7) "I'm a motorcyclist in the bike lane!"
All the time, especially during rush hours. I walk about a half mile to the farther tro-tro station on Tuesdays when I volunteer at the Embassy (I'm faster than the traffic and its easier to catch a tro-tro down there), and I see probably 10-15 motorcyclists in the bike lane at that time. These bike lanes are a section of the sidewalk too, not a section of the street. There is a curb between the bike lane and the street. It seems so progressive that they are there, until Matt gets chastised by a motorcyclist for riding his bike in the bike lane rather than on the sidewalk. Note, these motorcyclists are driving up to 50 mph.
8) "I'm a taxi driver and I know that other taxi driver! Hi, friend!"
I like this one, because just when I'm about to get annoyed that yet another taxi is accosting me for walking, I see that no, they are just being friendly to a coworker.
9) "I am going to drive where you are walking, but I'll wait for you to pass... Hurry up, though!"
This is especially confusing as #3 is so much more common, but it's nice to hear. Often, they flash their lights at you too, which helps to distinguish whether they want you to stop or keep going.
10) "Hey, obruni!"
A lot of times people yell this at us because they want to meet us, or sell us something. But sometimes they yell it because they are just excited to see a white person. Imagine if you walked down the street and saw a Kenyan guy and said, "Hey! Black person!" Well, it's nothing like that here. The proper response is a smile and nod, and, if you can, "EtE sen?" or "Obibini!!" ("how are you?" and "Black person", respectively).
I don't like making posts without pictures, so here is a lion. These don't live in Ghana.