Plagman's passion for puppeteering and cameras brought him to the show in 1977. Director Ton Hasebos took him on right away. Plagman thinks because of his great enthusiasm. He began his Sesamstraat career performing Pino in 1979. He started performing Tommie in 1980, sharing the part with other performers. Plagman has given Tommie his hoarse voice and invented various exclamations which are now part of the Dutch language, like "poe hee!" and "hotseflots!"
Plagman's non-Henson TV puppetry work includes Koekeloere and WaWa. He also directs beginning puppeteers and performs in the stage show Kapitein Winocchio.