Referrer spam is a widespread problem for Google Analytics accounts.
To find referrer spam in your Google Analytics you should:
Step 1: Navigate to Referral Traffic in Google Analytics
Step 2: Filter by bounce rate, looking for referrers with a 100% or 0% bounce rate and 10 or more sessions. Most likely they are spam referrers.
Step 3: Make a copy of spam referrers and if you're not sure then search online with the referrer name and "referrer spam".
Step 4: When you have identified referrer spam then follow the steps in our article to remove it from your Google Analytics.