Instagram blocked the eggplant emoji in in search back in 2015 [0], and there are vibrators that look like eggplants [1]. If you spam eggplants in a chat chances are the other participants will know the hidden meaning and wonder what you're trying to say.

[0] http://money.cnn.com/2015/04/29/technology/eggplant-instagra...

[1] https://emojibator.com/