Like a wild animal.
Ever read Groo the Wanderer? By Sergio Aragonez? Everyone hates him, nobody can beat him in battle, he's thick as a brick, and almost as smart. By the end of the comic series his enemies killed themselves and sunk their own ships because it was safer... He would see a battle and go "A Frey!" Pull out these two masterwork Katana, charge in and slaughter everyone. ON BOTH SIDES! Couldn't read, write, tell time. No manners. Extreme bad luck. Low DEX. Except when it came to battle. High ST and CON. Low CHA. People used to try and use him for their own gain, but in the end just cringed and tried to get away when they saw him coming.
Life is like a box of cho-kill-its.
I know he's not smart, so clever ideas and plans are out.
Highly technical or multi-step plans are out, but not necessarily "clever" ones when you have an above-average Wisdom. An "intelligent" person knows all sorts of things about design specs and technical fixes when it comes to fixing a gadget that won't run; a "wise" person comes in, changes the battery/reads the instructions and gets it working.
As a fighter with a good wisdom score, undoubtedly you can know clever ways of disabling a foe, negating their advantages or otherwise ending fights quickly. You can grasp small details and shifts in the odds just fine, and probably put them together "in the moment," but multi-step tactics or long-term strategies might be beyond your ken unless you've been shown them first and practiced them over a few times. You probably don't have a lot of mental patience for things you aren't interested in to begin with, and aren't going to wait for people to "get to the good part" without a reason.
With a charisma of 5, you can either play the guy who wants to get along with others but can't grasp that he's really annoying (or why), or you can play the guy who is pretty loyal but extremely standoffish and dismissive of everybody (not recommended). Cattoy's allusion above is a really good one for the former, and it makes more sense if your DM has stipulated that you were childhood friends and have to get along.
He's not intellectual, but he is intuitive. He notices things other might miss, but doesn't know what they mean in the grand scheme of things. He's tactless: he says what he sees and he doesn't understand why people get upset ("The emperor has no clothes.").
I've played a simlar character before when the dice rolls were not kind. I played a dwarven fighter with an INT of 5, a WIS of 12, and a CHA of 7 (So fairly similar to your situation).
I played him as straightforward guy who lived 'in the moment'. He liked what he liked, hated what he hated, made no apologies for his opinions and said what was on his mind. He formed views on things quickly and simplistically, and was very difficult to change his focus when he was set on something.
He wasnt always negative or difficult, but he wouldnt sugarcoat it if something needed to be said (in his opinion). He'd get frustrated and bored in planning sessions, and generally wander off.
He never lied because it was too complicated to remember. He once tried to 'doublecross' a villain who was trying to recruit him by telling him that he'd probably have to hit him with an axe soon, so they couldnt be friends "for long".
The important thing is that he didnt act suicidally or in a reckless manner. A high WIS means that he was quite practical, his actions just werent complicated or multi-layered
He turned out to be one of the most fun and memorable characters I've ever played, and was very popular with the other players. Having a Low CHA means difficult interactions in game, not around the table. If your character acts like a tool and endangers the party or obstructs the game goals (such as deliberately pissing off important NPCS) he will be a significant liability, but if played as a slightly dense, blunt but ultimately well meaning individual you can enhance the RP experience for everyone.
Thuggish cop or thuggish robber. In either case, someone who is gruff, abrasive, or overaggressive, not especially bright but pretty canny and street smart, notices suspicious characters or things that are out of place, has a well-developed sense for negotiating a 'hood, can walk into a tavern, scan the crowd, and get a good feel for people's character and motivations.