There are over 200 different species of Bufo toads, the most commonly known, being Bufo alvarius mainly found in the Sonoran desert in North America; The Bufo Marinus native to the Amazon and the European Bufo Vulgaris.
All Bufo toads have multi- cellular glands on their neck and limbs; these glands produce many different biologically active compounds, which vary from species to species. All Bufo toads excrete Bufotenine. It is still disputed over whether Bufotenine is actually psychoactive. The Bufo Alvarius is the only known toad to produce 5-Meo-DMT. 5-Meo-DMT is a hallucinogenic that is said to have effects similar to psilocybin and DMT.

The Bufo toad has been used in many different ways throughout the world.
Tribes have used the skin or venom of Bufo toads for centuries in medicines and for hallucinogenic rituals, they have been documented as far back as 2000 BC. Bufo toads and other toads were included in many cultural charms for sexuality and rain fertility since the earliest of times. They've been used in burial services, and have been found in large numbers at burial sites, in Mexico. Chinese healers have been using Bufo venom in a potion called ch'an su for thousands of years. Bufo toads have played a part in medicinal history in Nepal, Tibet, India, Germany and Africa for hundreds of years. Bufo toads were also used for hallucinogenic rituals. I.
The Bufo Alvarius probably wasn't used in most of the rituals, being that it is almost exclusive to the Sonoran desert.
Many Bufo toads used for hallucinogenic or psychedelic experiences were of another Bufo spices. As Bufo Alvarius is the only toad to produce 5-Meo-DMT, it must have been another active component in the toad's venom that produces mind-altering effects. Almost certainly Bufotenine is this active component producing these effects, even though this isn't confirmed.

5-Meo-DMT was first synthesized in the 1930s, but its mind-altering effects weren't uncovered for many more years. In the late 1950s it was found that 5-Meo-DMT was the main active compound found in the hallucinogenic snuffs, prepared from seeds, barks, stems and flowers in several South American tribes.
In 1968 when 5-Meo-DMT was found in the Bufo Alvarius, word spread of the 'psychedelic toad'. It was in the United States where the act of 'toad licking' started, and word spread. Licking toads to 'get high' is still an urban myth, and even though the venom of the Bufo alvarius contains 5-Meo-DMT, a very potent hallucinogenic, it is inactive when taken orally.
To get the best out of the venom (5-Meo-DMT) the venom needs to be collected, dried and then smoked in a pipe.

To extract the venom from the toad without harming it is relatively easy. Pick the toad up and hold firmly in one hand. You'll need a smooth glass or plastic slide roughly 10 inches square. Fix the slide in a horizontal position and hold the toad in front of it. Squeeze gently at the base of the gland until the venom squirts out on to the plate. Do this to all the glands on the limbs and neck, collecting all the venom on the glass plate. (The toads' glands are then empty and need at least 4 weeks to regenerate). The milky white venom starts drying within minutes. Scrape the venom from the plate and dry thoroughly. The venom is then ready to smoke; it can also be stored in an air tight container. Only a tiny amount of venom needs to be used for a hallucinogenic experience, about the size of a match head. Shave it into thin slices and use in a one-hit pipe with a gauze/screen. Light the venom with a good flame and smoke in one inhalation. Hold in for as long as possible to try and absorb the full dose in one breath for a better high. Within a minute you will be overwhelmed with strong psychoactive effects, you will be completely absorbed in an overload of thoughts and perception. The initial intense hit soon fades in to a calm LSD-like sensation, with visual illusions and hallucinations; colours may seem brighter and more beautiful. Most likely, you will experience euphoric moods with bursts of unmotivated laughter. The duration of the 'psychedelic trip' is quite short, and hallucinogenic effects decrease rapidly. The whole cycle is over in roughly 15 minutes. There seems to be no hangover, and some say there is an afterglow after smoking the venom that can last for a few hours.
There have been no reported toad smoking casualties to date, but there is no proof that the drug is completely safe in the long run.