The glamour girl, 23, who was involved in Vernon Kay's sex-text scandal earlier this year, reportedly slept with Best after attending an event at Alton Towers theme park.
Sugden spent the night with the Celebrity Love Island star at a hotel in Staffordshire, according to The Sun.
"Rhian and Calum were flirting as the drinks flowed and ended up getting it on," said an insider. The following day, the 29-year-old tweeted Sugden, joking: "Typical, you ordered extra sausage."
Best is currently working on new online reality series Temptation Villa, which will follow 16 people who join him on holiday in Ibiza to party like celebrities.