A classic nod on number 69, note the number 69 on the runway
number 69 is an innuendo of the 69 sex position, a recurring gag throughout the series. This page lists some of its appearances in their respective games:
Grand Theft Auto
Grand Theft Auto III
Grand Theft Auto: Vice City
The Marquis has "Marquis 69" written on the rear of the boat.
The number can be found on some of the Bloodring Bangers as badges.
Grand Theft Auto: San Andreas
Thrust (Note the 69 right)
Another magazine in CJ's safehouses, Thrust, says "69 ways to reach your driving climax!".
"69" stickers can be found on a number of containers on the FleischBerg factory near Blueberry. The containers also surround a stunt jump.
The San Fierro 69ers American Football team which is also a reference to the San Francisco 49ers.
The Golden Palms in Los Flores.
Ideal Living magazine.
The front page of the Ideal Living magazine in Carl's safehouses claims it has "369 ideas for your home".
Runways at all major airports in the game have the number 69 on both ends of the runways.
The abandoned Hi K69 radio station in Fort Carson.
In a Burger Shot advertisement on a billboard, one of their Meals on the billboard costs 69 cents.
On the loading screen featuring Sweet and Ryder selling what appears to be drugs, on the table there is a napkin with the number 69 written all over it.
In the achievement "Metrosexual", where the player must spend $6,969 on clothing, hairstyles and tattoos.
Population of Fort Carson is 369.
Grand Theft Auto: Liberty City Stories
Grand Theft Auto IV
There is brand of Cuban cigars called 69 Brand.
The achievement and trophy Get Good Wood (which is also a sexual reference itself) in is earned by whacking 69 bikers off their bikes with a bat during The Lost and Damned motorbike races.
LCPD officers have the number 69 on their uniform collars.
The strippers in have $69 bills strapped to their body.
During his TV skit at Split Sides, Katt Williams mentions Liberty City's high gas prices, humorously stating that gas costs $69 a gallon.
Many of the parking stack in Liberty City has a sign that reads: '$8.69 per 1/2 hour' (one example can be seen on the parking lot in front of Lucky Winkles).
Grand Theft Auto V
The Police Bike's front fender in GTA V. Note the identification number on the fender.
There are various graffiti on the back of the Vinewood Sign which say 69.
One of the Snapmatic picture borders has text that reads 0069.
On Michael's personal vehicle, on all four of the wheels, there are dollar signs. But if the wheels are turned to a horizontal degree, it appears that the dollar signs are actually a very well, clever hidden illusion showing 69.
 On Devin Weston's website "bedevinweston.com" there is a quote written by Devin "6 black belts, 9 inches"
There is a clothing store on Portola Drive in Los Santos called Sessanta Nove. Sessanta Nove means "69" in Italian.
In the Beta, Route 68 was originally going to be called 'Route 69'.
The parking garage in Pillbox Hill has a billboard on the top that says "Park here for only $69 a day!" This is the same garage used in the GTA Online mission The Parking Garage.
At a Xero Gas Station in Pacific Bluffs, the prices of fuel are displayed on the main pay-out-booth, with one of them reading 469. Furthermore, the 4 has slightly fallen off, clearly showing the 69.
One of the songs on WorldWide FM is Roman GianArthur's "I-69" (added in the enhanced version).