A Super kebab is a slightly better version of a Kebab. Red hot sauce was added to make it spicy. It is sold by Ali the Kebab seller. The sole advantage of the Super kebab appears to be that, unlike the normal Kebab, it may affect Summoning, Slayer, Runecrafting or Firemaking. It may also simply do nothing.
To make a Super kebab, the player must use Red hot sauce (bought from Ali the Kebab seller) on either a normal Kebab or Ugthanki kebab.
When the super kebab was first released, it was unintentionally tradeable with non-members, who could not obtain it in any other way. Shortly after this glitch was discovered by players, Jagex updated the game so that they were members-only.
Although you can buy the kebab for 5 coins, you can also buy a regular kebab for 3 coins from Ali and ask for his Red hot sauce and use it on the kebab, so essentially, you got it for 3 coins total.