A tactile hallucination is the experience of perceiving a convincing physical sensation that is not actually occurring.   Common examples of this can include people or insects  touching the body in various places and in a wide variety of ways. Alternatively, these hallucinations can be felt as complex and structured arrangements of vibration or pressure across the skin.
This effect may be also accompanied by visual hallucinations of a plausible cause related to the sensation. For example, during internal and external hallucinations, one may be able to touch and feel imagined objects or autonmous entities just as convincingly as within normal everyday dreams. The sensations that are possible within these hallucinations are nearly limitless and can even include pain or sexual pleasure.
Tactile hallucinations are most commonly induced under the influence of heavy dosages of deliriants compounds, such as DPH, datura, and benzydamine. However, they can also occur to a lesser extent under the influence of psychedelics, stimulant psychosis  and extreme sleep deprivation.
- Tactile hallucinations: conceptual and historical aspects | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC491362/
- Tactile hallucinations: conceptual and historical aspects | https://www.ncbi.nlm.nih.gov/pubmed/19521636
- Delusory Parasitosis by Nancy C. Hinkle | https://web.archive.org/web/20121021033308/http://www.ent.uga.edu/pubs/delusory.pdf
- Tactile hallucinations with repetitive movements following low-dose cocaine: implications for cocaine reinforcement and sensitization: case report. (ncbi) | https://www.ncbi.nlm.nih.gov/pubmed/23414508